Has anyone on this list tried to reproduce this, either using (or not
using) Kefah's included test scripts?
On Feb 24, 2005, at 11:21 AM, Kefah T. Issa wrote:
>
> Dear Subversion developers,
>
> I've been running load testing on Svn updates through httpd (apache /
> mod_dav_svn).
>
> I am updating 100 clients similtanuously who are one revision a way
> from the svn head; I am using fsfs for svn back end
> to achieve pure-readonly updates; and to make it faster for svn to
> deliver the changeset (rev) just by handing the related sections in
> the db/revs/rev_num file. (where rev_num stands for the latest
> revision number)
>
> I checked the content of the xdelta tag in the xml response and found
> it to identically match sections of the db/revs/rev_num file.
>
> My assumption was that the mod_dav_svn(along with the backend svn
> libraries), once receiving a one-version difference update request
> would only care to grab that data and pass it back to the clients;
> apparently this is not the case; apache ends up consuming massive cpu
> load (reaching load average to 40 sometimes).
>
> Whats even more confusing was when trying to do a fresh checkout or
> direct grab of files over svn/http; cpu usage was almost negligible.
> This is confusing because, theoretically, this scenario should be the
> most cpu intensive because mod_dav_svn needs to reconstruct the latest
> files over the different previous revisions.
>
> After facing this un-justifiable cpu-load and consulting on #svn irc,
> I ended up writing to you the detailed secanrio here below.
>
> Note that I also ran this test against a quad-proc xeon debian server
> and was able to reproduce that issue as well.
>
> Thank you in advance,
>
> I must say that I feel truly grateful to the people who made this
> outstanding software possible.
>
> Let me know if you need any further details. Kindly respond to my
> email (kefah@freesoft.jo) as I am not subscribed to your mailing list.
>
> Best regards,
> Kefah T. Issa
>
> P.S. You can find attached the helper bash scripts I used to conduct
> my tests.
>
> # Hardware : 550 MHz PIII box
> # Software: Fedora Core 2 (updated using Atrpm repository with
> subversion 1.1.3)
> # ( RPMS : subversion-1.1.3-0_14.rhfc2.at,
> mod_dav_svn-1.1.3-0_14.rhfc2.at)
> # Svn using mod_dav_svn / Apache 2.0.51
>
> # Svn server lives in separete box than the svn clients running the
> load.
>
> # On svn server box; prepare ...
> # login as root, we are also using a predefined user named esam.
> ssh root@mytestbox
>
> # Create Http configuration file for our test svn repo.
> cat > /etc/httpd/conf.d/svn_loadtest.conf << EOF
>
> <Location /svnlt>
> DAV "svn"
> SVNPath "/home/esam/www/svnlt"
> AllowOverride None
> </Location>
>
> EOF
>
> # Create the needed svn repository
> su - esam
> mkdir www
> cd www
> svnadmin create --fs-type fsfs svnlt
>
> # exit user esam and return to root
> chown -R apache.apache /home/esam/www/svnlt
> chmod o+rx /home/esam/www
> chmod o+rx /home/esam
>
>
> # On the other box;from we run svn clients try checkouts and updates.
>
> # Run 100 concurrent checkouts for this 0-rev repo on another box
> using the attached create_working_copies.sh shell script.
> # Note that config.sh should be properly configured; as its using by
> the other shell scripts.
> # server loadaverage before : 0,0,0
> ./create_working_copies.sh
> # server load average after : 0.01,0,0
>
> # On another working copy, Create and add a 100 MB bin (empty / zero)
> file :
> cd myotherworkingcopy/svnlt
> dd if=/dev/zero of=onemb.bin count=1 bs=1MB
> svn add onemb.bin
> svn commit -m """ onemb.bin
>
> # Conclusion : Checking out empty (rev 0) repository consume
> negligible cpu.
>
> # Remove all checked out folder
> rm -fR wc_*
>
> # Run the create_working_copies
> ./create_working_copies.sh
> # load average on the server after finishing : 0.02, 0.01, 0.00
> # Conclusion : Checking out 1MB repository consumes negligible cpu.
>
> # From another working copy, add another 1 MB content to the original
> file and commt.
> cd myotherworkingcopy/svnlt
> dd if=/dev/zero of=onemb.bin count=1 bs=1MB seek=1
> svn commit -m """ onemb.bin
>
> # Update from rev1 to rev2
> ./update_working_copies.sh
>
> # Using top, monitor load average when that is taking place
> # serverside load average : 27,14,5
> # Conclusion : Updating a 1MB file diff consumes massive cpu resources.
>
>
> <config.sh><create_working_copies.sh><update_working_copies.sh>--------
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Received on Sun Feb 27 20:41:21 2005