We have a build machine running in our development department, which we've set up to build continuously throughout the working day.
What this does is:
Deletes the source code previously checked out (5 minutes)
Does a clean checkout from subversion (15 minutes)
Builds a whole bunch of C++ and .NET code (35 minutes)
Builds installers and run unit tests (5 minutes)
Given the above, what sort of impact would adding different hardware have on improving the time it takes to do the above?
For example - I was thinking about using an SSD for the harddisk as compiling involves a lot of random disk access.
The subversion server is currently a virtual machine - would switching it to be a physical machine help the slow checkout?
What impact would upgrading from a Core 2 Duo processor to an i7 make?
Any other suggestions on speeding up the above?
One trick that might speed up the SVN checkout process could be to have a working copy on the build machine, update the working copy and do a svn export from the working copy to the build directory. This should reduce the load on the SVN server and reduce network traffic.
Another trick to reduce the first 5 minutes of cleaning could be to move the old build dir to a temp folder on the same disk and then use another background task to delete the old build dir when the main build completes (could be a nightly cleanup task).
I think you've made good suggestions yourself. Definitely add a faster hard-drive (SSD or otherwise) and upgrade the CPU as well. I think your code repository (Subversion) should definitely be on a physical machine, ideally separate from your build machine. I think you'll notice a big difference after upgrading the hardware. Also, make sure the machine doesn't have any other large tasks running at the same time as the build tasks (e.g. virus scanning) so that the build tasks aren't slowed down.
How is your build machine setup to execute its tasks? Are you using continuous integration software? Is the machine itself a server or just a regular desktop machine?
Another way to speed up SVN is to use binary protocol instead of HTTP.
It looks like the build time is the most time consuming part - that's the best candidate for optimization. What about parallel build spread over other machines in the office - products like Incredibuild might significantly improve compilation time.
Related
We are running TeamCity with 20-ish .Net build configurations. All of them uses MSBuild 4.0. We recently moved one of our build agents from a machine running Windows Server 2008 to a new physical server running Windows Server 2012, and after this migration all the builds are taking almost twice as long time to finish, compared to on the old server! The new server is more powerful than the old server, both in terms of CPU, RAM and Disk. We have been running benchmarks on both servers, all of them confirming that the new server should be more capable than the old one.
According to the build logs it seems that all the stages of the build is slower, so it's not just one of the build steps that are slower.
First thing we did was to check the CPU utilization during builds, and it is suspiciously low! Only 3-6% CPU usage on some of the cores. RAM usage was also very low. Could it be some config for the build agent that is slowing down the builds, and that we have overlooked?
Note: The new server is running as a virtual machine. At first we thought that was the reason, but then that should have been reflected on the benchmarks? This is the only virtual machine running on this physical server, and it has almost all HW resources dedicated. Would be interesting to hear if any of you have had similar bad experience with running the build server on a virtual machine. We have also tried booting "natively" from the VHD image, without any difference in the build times.
I know this could be a very tricky one to debug for "external" people, but I was hoping that someone could maybe give some good suggestion on where to look for the issue, as we are kind of stuck right now.
Edit: Tried activating the Performance Monitor tool in TeamCity, and it shows that both CPU, RAM and Disk usage is comfortably running at <10% (Disk access peaked at 35% a couple of times during the build)
Our Jenkins server(linux machine) slows down over a period of time and it gets unresponsive. All the jobs take unexpectedly long time(even though they run on slaves which are different machines from server). One of things I have observed is increase in the number of open files. The number seems to be increasing as shown in the image below. Does anyone have a solution to keep check on this without restarting the server? Also, are there any configurations/tweaks that could improve the performance of the jenkins server?
We are using Jenkins for four years and we tried to keep it up-to-date (Jenkins + plug-ins).
Like you we experimented some inconvenience, depending on new versions of Jenkins or plug-ins...
So we decided to stop this "continuous" upgrade
Here are humble tips:
Avoid technical debt. Update Jenkins as much as you can, but use only "Long Term Support" versions (latest is 2.138.2)
Backup your entire jenkins_home before any upgrade!
Restart Jenkins every night
Add RAM to your server. Jenkins use file system a lot and this will improve caching
Define JVM min/max memory parameters with the same value to avoid dynamic reallocation, for example: -Xms4G -Xmx4G
Add slaves and execute jobs only on slaves
In addition to above, you can also try:
Discarding old builds
Distribute the builds on multiple slaves, if possible.
I know this is not so much a programming question but it is relevant.
I work on a fairly large cross platform project. On Windows I use VC++ 2008. On Linux I use gcc. There are around 40k files in the project. Windows is 10x to 40x slower than Linux at compiling and linking the same project. How can I fix that?
A single change incremental build 20 seconds on Linux and > 3 mins on Windows. Why? I can even install the 'gold' linker in Linux and get that time down to 7 seconds.
Similarly git is 10x to 40x faster on Linux than Windows.
In the git case it's possible git is not using Windows in the optimal way but VC++? You'd think Microsoft would want to make their own developers as productive as possible and faster compilation would go a long way toward that. Maybe they are trying to encourage developers into C#?
As simple test, find a folder with lots of subfolders and do a simple
dir /s > c:\list.txt
on Windows. Do it twice and time the second run so it runs from the cache. Copy the files to Linux and do the equivalent 2 runs and time the second run.
ls -R > /tmp/list.txt
I have 2 workstations with the exact same specs. HP Z600s with 12gig of ram, 8 cores at 3.0ghz. On a folder with ~400k files Windows takes 40seconds, Linux takes < 1 second.
Is there a registry setting I can set to speed up Windows? What gives?
A few slightly relevant links, relevant to compile times, not necessarily i/o.
Apparently there's an issue in Windows 10 (not in Windows 7) that closing a process holds a global lock. When compiling with multiple cores and therefore multiple processes this issue hits.
The /analyse option can adversely affect perf because it loads a web browser. (Not relevant here but good to know)
Unless a hardcore Windows systems hacker comes along, you're not going to get more than partisan comments (which I won't do) and speculation (which is what I'm going to try).
File system - You should try the same operations (including the dir) on the same filesystem. I came across this which benchmarks a few filesystems for various parameters.
Caching. I once tried to run a compilation on Linux on a RAM disk and found that it was slower than running it on disk thanks to the way the kernel takes care of caching. This is a solid selling point for Linux and might be the reason why the performance is so different.
Bad dependency specifications on Windows. Maybe the chromium dependency specifications for Windows are not as correct as for Linux. This might result in unnecessary compilations when you make a small change. You might be able to validate this using the same compiler toolchain on Windows.
A few ideas:
Disable 8.3 names. This can be a big factor on drives with a large number of files and a relatively small number of folders: fsutil behavior set disable8dot3 1
Use more folders. In my experience, NTFS starts to slow down with more than about 1000 files per folder.
Enable parallel builds with MSBuild; just add the "/m" switch, and it will automatically start one copy of MSBuild per CPU core.
Put your files on an SSD -- helps hugely for random I/O.
If your average file size is much greater than 4KB, consider rebuilding the filesystem with a larger cluster size that corresponds roughly to your average file size.
Make sure the files have been defragmented. Fragmented files cause lots of disk seeks, which can cost you a factor of 40+ in throughput. Use the "contig" utility from sysinternals, or the built-in Windows defragmenter.
If your average file size is small, and the partition you're on is relatively full, it's possible that you are running with a fragmented MFT, which is bad for performance. Also, files smaller than 1K are stored directly in the MFT. The "contig" utility mentioned above can help, or you may need to increase the MFT size. The following command will double it, to 25% of the volume: fsutil behavior set mftzone 2 Change the last number to 3 or 4 to increase the size by additional 12.5% increments. After running the command, reboot and then create the filesystem.
Disable last access time: fsutil behavior set disablelastaccess 1
Disable the indexing service
Disable your anti-virus and anti-spyware software, or at least set the relevant folders to be ignored.
Put your files on a different physical drive from the OS and the paging file. Using a separate physical drive allows Windows to use parallel I/Os to both drives.
Have a look at your compiler flags. The Windows C++ compiler has a ton of options; make sure you're only using the ones you really need.
Try increasing the amount of memory the OS uses for paged-pool buffers (make sure you have enough RAM first): fsutil behavior set memoryusage 2
Check the Windows error log to make sure you aren't experiencing occasional disk errors.
Have a look at Physical Disk related performance counters to see how busy your disks are. High queue lengths or long times per transfer are bad signs.
The first 30% of disk partitions is much faster than the rest of the disk in terms of raw transfer time. Narrower partitions also help minimize seek times.
Are you using RAID? If so, you may need to optimize your choice of RAID type (RAID-5 is bad for write-heavy operations like compiling)
Disable any services that you don't need
Defragment folders: copy all files to another drive (just the files), delete the original files, copy all folders to another drive (just the empty folders), then delete the original folders, defragment the original drive, copy the folder structure back first, then copy the files. When Windows builds large folders one file at a time, the folders end up being fragmented and slow. ("contig" should help here, too)
If you are I/O bound and have CPU cycles to spare, try turning disk compression ON. It can provide some significant speedups for highly compressible files (like source code), with some cost in CPU.
NTFS saves file access time everytime. You can try disabling it:
"fsutil behavior set disablelastaccess 1"
(restart)
The issue with visual c++ is, as far I can tell, that it is not a priority for the compiler team to optimize this scenario.
Their solution is that you use their precompiled header feature. This is what windows specific projects have done. It is not portable, but it works.
Furthermore, on windows you typically have virus scanners, as well as system restore and search tools that can ruin your build times completely if they monitor your buid folder for you. windows 7 resouce monitor can help you spot it.
I have a reply here with some further tips for optimizing vc++ build times if you're really interested.
The difficulty in doing that is due to the fact that C++ tends to spread itself and the compilation process over many small, individual, files. That's something Linux is good at and Windows is not. If you want to make a really fast C++ compiler for Windows, try to keep everything in RAM and touch the filesystem as little as possible.
That's also how you'll make a faster Linux C++ compile chain, but it is less important in Linux because the file system is already doing a lot of that tuning for you.
The reason for this is due to Unix culture:
Historically file system performance has been a much higher priority in the Unix world than in Windows. Not to say that it hasn't been a priority in Windows, just that in Unix it has been a higher priority.
Access to source code.
You can't change what you can't control. Lack of access to Windows NTFS source code means that most efforts to improve performance have been though hardware improvements. That is, if performance is slow, you work around the problem by improving the hardware: the bus, the storage medium, and so on. You can only do so much if you have to work around the problem, not fix it.
Access to Unix source code (even before open source) was more widespread. Therefore, if you wanted to improve performance you would address it in software first (cheaper and easier) and hardware second.
As a result, there are many people in the world that got their PhDs by studying the Unix file system and finding novel ways to improve performance.
Unix tends towards many small files; Windows tends towards a few (or a single) big file.
Unix applications tend to deal with many small files. Think of a software development environment: many small source files, each with their own purpose. The final stage (linking) does create one big file but that is an small percentage.
As a result, Unix has highly optimized system calls for opening and closing files, scanning directories, and so on. The history of Unix research papers spans decades of file system optimizations that put a lot of thought into improving directory access (lookups and full-directory scans), initial file opening, and so on.
Windows applications tend to open one big file, hold it open for a long time, close it when done. Think of MS-Word. msword.exe (or whatever) opens the file once and appends for hours, updates internal blocks, and so on. The value of optimizing the opening of the file would be wasted time.
The history of Windows benchmarking and optimization has been on how fast one can read or write long files. That's what gets optimized.
Sadly software development has trended towards the first situation. Heck, the best word processing system for Unix (TeX/LaTeX) encourages you to put each chapter in a different file and #include them all together.
Unix is focused on high performance; Windows is focused on user experience
Unix started in the server room: no user interface. The only thing users see is speed. Therefore, speed is a priority.
Windows started on the desktop: Users only care about what they see, and they see the UI. Therefore, more energy is spent on improving the UI than performance.
The Windows ecosystem depends on planned obsolescence. Why optimize software when new hardware is just a year or two away?
I don't believe in conspiracy theories but if I did, I would point out that in the Windows culture there are fewer incentives to improve performance. Windows business models depends on people buying new machines like clockwork. (That's why the stock price of thousands of companies is affected if MS ships an operating system late or if Intel misses a chip release date.). This means that there is an incentive to solve performance problems by telling people to buy new hardware; not by improving the real problem: slow operating systems. Unix comes from academia where the budget is tight and you can get your PhD by inventing a new way to make file systems faster; rarely does someone in academia get points for solving a problem by issuing a purchase order. In Windows there is no conspiracy to keep software slow but the entire ecosystem depends on planned obsolescence.
Also, as Unix is open source (even when it wasn't, everyone had access to the source) any bored PhD student can read the code and become famous by making it better. That doesn't happen in Windows (MS does have a program that gives academics access to Windows source code, it is rarely taken advantage of). Look at this selection of Unix-related performance papers: http://www.eecs.harvard.edu/margo/papers/ or look up the history of papers by Osterhaus, Henry Spencer, or others. Heck, one of the biggest (and most enjoyable to watch) debates in Unix history was the back and forth between Osterhaus and Selzer http://www.eecs.harvard.edu/margo/papers/usenix95-lfs/supplement/rebuttal.html
You don't see that kind of thing happening in the Windows world. You might see vendors one-uping each other, but that seems to be much more rare lately since the innovation seems to all be at the standards body level.
That's how I see it.
Update: If you look at the new compiler chains that are coming out of Microsoft, you'll be very optimistic because much of what they are doing makes it easier to keep the entire toolchain in RAM and repeating less work. Very impressive stuff.
I personally found running a windows virtual machine on linux managed to remove a great deal of the IO slowness in windows, likely because the linux vm was doing lots of caching that Windows itself was not.
Doing that I was able to speed up compile times of a large (250Kloc) C++ project I was working on from something like 15 minutes to about 6 minutes.
Incremental linking
If the VC 2008 solution is set up as multiple projects with .lib outputs, you need to set "Use Library Dependency Inputs"; this makes the linker link directly against the .obj files rather than the .lib. (And actually makes it incrementally link.)
Directory traversal performance
It's a bit unfair to compare directory crawling on the original machine with crawling a newly created directory with the same files on another machine. If you want an equivalent test, you should probably make another copy of the directory on the source machine. (It may still be slow, but that could be due to any number of things: disk fragmentation, short file names, background services, etc.) Although I think the perf issues for dir /s have more to do with writing the output than measuring actual file traversal performance. Even dir /s /b > nul is slow on my machine with a huge directory.
I'm pretty sure it's related to the filesystem. I work on a cross-platform project for Linux and Windows where all the code is common except for where platform-dependent code is absolutely necessary. We use Mercurial, not git, so the "Linuxness" of git doesn't apply. Pulling in changes from the central repository takes forever on Windows compared to Linux, but I do have to say that our Windows 7 machines do a lot better than the Windows XP ones. Compiling the code after that is even worse on VS 2008. It's not just hg; CMake runs a lot slower on Windows as well, and both of these tools use the file system more than anything else.
The problem is so bad that most of our developers that work in a Windows environment don't even bother doing incremental builds anymore - they find that doing a unity build instead is faster.
Incidentally, if you want to dramatically decrease compilation speed in Windows, I'd suggest the aforementioned unity build. It's a pain to implement correctly in the build system (I did it for our team in CMake), but once done automagically speeds things up for our continuous integration servers. Depending on how many binaries your build system is spitting out, you can get 1 to 2 orders of magnitude improvement. Your mileage may vary. In our case I think it sped up the Linux builds threefold and the Windows one by about a factor of 10, but we have a lot of shared libraries and executables (which decreases the advantages of a unity build).
How do you build your large cross platform project?
If you are using common makefiles for Linux and Windows you could easily degrade windows performance by a factor of 10 if the makefiles are not designed to be fast on Windows.
I just fixed some makefiles of a cross platform project using common (GNU) makefiles for Linux and Windows. Make is starting a sh.exe process for each line of a recipe causing the performance difference between Windows and Linux!
According to the GNU make documentation
.ONESHELL:
should solve the issue, but this feature is (currently) not supported for Windows make. So rewriting the recipes to be on single logical lines (e.g. by adding ;\ or \ at the end of the current editor lines) worked very well!
IMHO this is all about disk I/O performance. The order of magnitude suggests a lot of the operations go to disk under Windows whereas they're handled in memory under Linux, i.e. Linux is caching better. Your best option under windows will be to move your files onto a fast disk, server or filesystem. Consider buying an Solid State Drive or moving your files to a ramdisk or fast NFS server.
I ran the directory traversal tests and the results are very close to the compilation times reported, suggesting this has nothing to do with CPU processing times or compiler/linker algorithms at all.
Measured times as suggested above traversing the chromium directory tree:
Windows Home Premium 7 (8GB Ram) on NTFS: 32 seconds
Ubuntu 11.04 Linux (2GB Ram) on NTFS: 10 seconds
Ubuntu 11.04 Linux (2GB Ram) on ext4: 0.6 seconds
For the tests I pulled the chromium sources (both under win/linux)
git clone http://github.com/chromium/chromium.git
cd chromium
git checkout remotes/origin/trunk
To measure the time I ran
ls -lR > ../list.txt ; time ls -lR > ../list.txt # bash
dir -Recurse > ../list.txt ; (measure-command { dir -Recurse > ../list.txt }).TotalSeconds #Powershell
I did turn off access timestamps, my virus scanner and increased the cache manager settings under windows (>2Gb RAM) - all without any noticeable improvements. Fact of the matter is, out of the box Linux performed 50x better than Windows with a quarter of the RAM.
For anybody who wants to contend that the numbers wrong - for whatever reason - please give it a try and post your findings.
Try using jom instead of nmake
Get it here:
https://github.com/qt-labs/jom
The fact is that nmake is using only one of your cores, jom is a clone of nmake that make uses of multicore processors.
GNU make do that out-of-the-box thanks to the -j option, that might be a reason of its speed vs the Microsoft nmake.
jom works by executing in parallel different make commands on different processors/cores.
Try yourself an feel the difference!
I want to add just one observation using Gnu make and other tools from MinGW tools on Windows: They seem to resolve hostnames even when the tools can not even communicate via IP. I would guess this is caused by some initialisation routine of the MinGW runtime. Running a local DNS proxy helped me to improve the compilation speed with these tools.
Before I got a big headache because the build speed dropped by a factor of 10 or so when I opened a VPN connection in parallel. In this case all these DNS lookups went through the VPN.
This observation might also apply to other build tools, not only MinGW based and it could have changed on the latest MinGW version meanwhile.
I recently could archive an other way to speed up compilation by about 10% on Windows using Gnu make by replacing the mingw bash.exe with the version from win-bash
(The win-bash is not very comfortable regarding interactive editing.)
How do I improve Subversion client update performance? It appears to be disk bound on the client.
Details:
CollabNet Windows client version 1.6.2 (r37639)
Windows XP SP2
3 GB RAM with PF Usage around 1 GB and System Cache of 1.1 GB.
Disk has write caching enabled
Update takes 7-15 minutes (when very little to update).
Checkout has 36,083 directories/files (from svn list)
Repository has 58,750 revisions.
Checkout takes about 2.7 GB
Perf monitor shows % Disk Write time stays near 90% during update.
Max Disk Read Bytes/sec got up to 12.8M and write got up to 5.2M
CPU, paging file usage, and network usage are all low.
Watching the server performance seems to show that it isn't a bottleneck.
I'm especially interested in answers besides getting a faster disk (especially configuration changes).
Updates from some of the suggestions:
I need the whole thing so sparse directories won't work.
Another client (TortoiseSVN) takes 7 minutes also
TortoiseSVN icon overlays have be configured so they don't cause the problem.
Anti-virus is configured to to skip that directory is it isn't causing the problem.
I experience exatly the same thing. Recently replaced Perforce with svn, but if we cannot overcome the performance problems on Windows me must consider another tool.
Using svn 1.6.6, Win XP and Vista clients. RedHat server.
My observations matches yours:
Huge disk-write activity.
Antivirus not a bottleneck.
No matter witch svn-clients are used.
No server or network bottleneck.
Complementary info
More than 3 times faster operations on:
Linux (Ubuntu).
Linux (Ubuntu) running on VirtualBox at Win Vista host.
Win XP running on VMWare at RedHat host.
Do you need every bit of the repository on your working copy? If you truly only care about particular portions of the tree, look into Subversion's Sparse Directories (a.k.a. "Sparse Checkouts") feature. It allows you to manipulate your working copy so it only contains those directories of interest.
Just as an example, you might use this to prune documentation, installer-related files, etc. Depending on what you truly need on your local machine, embracing this approach could make a serious dent in your wait times.
Try svn client version 1.5.. It helped me on my Vista laptop. Versions 1.6. are extremely slow.
This is more likely to be your network and the amount of data moved as well as your client. Are you using Tortoise? I find it to be a bit slow myself when moving that much data!
Are you using TortoiseSVN? If so, the Icon Overlays do slow down operations. If you go to TortoiseSVN Settings/Icon Overlays there are several settings you can tweak to control the level to which you want to use the Overlays, including turning them off completely. See if that affects your performance.
Do you run a virus checker that uses on-access scanning? That can really make it crawl. If so, turn it off and see if that helps. Most scanners will have a way to exclude specific directories if that helps.
Nobody seems to be pointing out the one reason that I often consider a design flaw. Subversion creates a second "pristine" copy of the checkout for offline operations. If you're checking out 4G of files, it's actually writing 8G to disk.
Compare a checkout to an export. That will show you the massive difference when writing those second copies.
There's nothing you can do about that.
Upgrade to svn 1.7
From Discussion of Slow Performance of SVN Update:
The update process in svn 1.6 goes something like this:
search the entire working copy, to see what's there at the moment, and locking it so no one changes the answer during the next steps
tell that to the server
receive from the server whatever new stuff you need, applying the changes to the files as you go
recurse over the entire working copy again, unlocking it
If there are many directories and files, steps 1 and 4 can take up a
lot of time. This would be consistent with your observation of long
delays with no network traffic.
Working copy format was changed in svn 1.7. Now all meta information is stored in SQLite database in root folder of working copy and there is no need to perform steps 1 and 4 any more which consumed most of the time durring svn update.
I'm experiencing painfully slow operations with one of our SVN repositories/projects.
For example, it's taking 5-10 minutes to revert the changes in one small file (10 KB). Or about 40-60 minutes to check out the project of 100 MB.
There are about 30 other projects on the same server, some vastly bigger than this one, and none of them preform like this.
One thing to note is that this project is a Magento project. It's not very large in terms of disk space, but I have 23k Files and 11k folders, and I have read SVN preforms badly when there are lots of little files; is this true? And is there anything I can do to speed things up?
The Subversion working copy performs quite badly when there's a huge number of directories, like in your case. For write operations (even only locally) to the working copy, the working copy has to be locked, which means that a lock file is created in every directory (that's 11k file creates), then the action executes, and the those 11k files are deleted again.
Subversion 1.7 is moving to a different working copy format, that should resolve these problems. Until then there's a few tricks you might try to speed things up, like excluding the working copy from your virus scanner, disabling file monitors on the directory (like TortoiseSvnCache), and trying to reduce the total number of directories. (Perhaps by checking out a few separate working copies)
There is a known issue with the use of the recycle bin with revert which causes slow reverting. Emptying your recycle bin and setting TortoiseSVN not to use it during revert operations both speed up this operation (see http://www.nabble.com/Revert-is-too-slow-td18222196.html).
This has definitely sped up my revert operations.
I experienced extreme slowness with Subversion on Windows after changing my password. I had to delete all directories and files from %APPDATA%\Subversion\auth.
Now SVN is fast as a hare. My slowness occurred via both TortoiseSVN and the command line.
SVN is slow if you use NFS (Network File System) for the working copy. This could be your problem.
We have face similar issue, the problem was TortoiseSvn (Version 1.9.7). For example, the repo browser took about 10 minutes to initial.
We have turned of the Show Locks feature and every thing fixed!
Right click on a folder and select Tortoise\Settings then General\Dialog 3 then deselect Show Locks
Also some good hints can be found at http://tigris-scm.10930.n7.nabble.com/Workaround-for-slow-RepositoryBrowser-on-large-repositories-td92324.html
Reverting changes in SVN is a local operation which shouldn't go to the server at all. So it sounds as though the problem is in your working copy of the project.
Try running 'svn cleanup' in the working copy; you may also want to check if you have problems with the hard drive or filesystem.
Our SVN was running painfully slow through TortoiseSVN, Eclipse and command line. Commits and exports were slow. Our Zend Framework-based PHP projects would take an age to update and popping in a small commit of about three files would take 5-10 minutes.
Our SVN virtual machine (CentOS) only had 700 MB of RAM which seemed reasonable for a Linux CLI only running Subversion via Apache and has been running fine for about one year. We've only got about 20 projects and only three developers.
I've upped it to 1.5 GB of RAM and things are running much faster now, back to our old speeds.
I also suffered a large slowdown after upgrading to TortoiseSVN 1.7.3.
Then I discovered I had a separate install of SVN 1.6.5. I uninstalled both and reinstalled TortoiseSVN and now things are much better. First update of the day in TortoiseSVN is still slow (1-2 minutes), but fast after that.
I have some projects which use the Eclipse IDE. If you capture the Eclipse project directories you get hundreds and hundreds of tiny files which has the same effect for my project as you're suffering on yours.
I think that when you check files out SVN does so one at a time which means that projects with huge numbers of files are always going to be slow and there's not much you can do about it (aside from avoiding frequent whole-repository operations).
Making changes to a single file shouldn't be slow though.
You may try the suggestions in another post on Stack Overflow about slow SVN. It could also be due to using a BDB database.