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Re: issue #1429 progress: ra_dav changing analogously to ra_svn

From: Tobias Ringström <tobias_at_ringstrom.mine.nu>
Date: 2003-10-28 01:44:02 CET

kfogel@collab.net wrote:
> Here's an update re recent progress on the performance front:

Cool. Thanks for writing this.

> This change results in an appx 300% for remote checkout, over a link
> with average 81 ms latency -- the Chicago office's T1 line to
> CollabNet HQ in California. Here are some timed checkouts of the
> Subversion r7428 tree, over CVS, stock Subversion, and Subversion with
> the patch:
> CVS SVN r7531 SVN r7531 + patch
> ---------- ---------- -----------------
> 1m21.733s 4m46.052s 1m1.295s
> 1m21.528s 4m21.998s 0m50.425s
> 1m24.678s 4m12.330s 0m55.898s
> 1m23.955s 3m52.263s 0m56.361s
> 1m25.752s 4m38.493s 0m51.013s
> This is know as a "win" :-).

This change is great, because it completely removes the (unneccessary)
latency performance problem. Unfortunately this does not tell us that
SVN is faster than CVS, as one might think from the numbers abobe. The
only reason SVN is faster here is because it compresses the data. If
you enable comression for CVS, the time will be very close to SVN time.
  But that does not tell us that they are about equally fast either. I
bet that for the CVS and SVN+patch tests above, you are using up all the
available bandwidth. That means that the performance of the SVN server
does not matter as long as it is fast enough to saturate the network.

If you increase the bandwidth, there comes a point where the checkout
time does not go below a certain time becuse the server cannot generate
data to transmit any faster, or because libsvn_wc cannot write the data
any faster. The throughput at that point is the real performance limit,
and I fear that CVS will still beat SVN by a wide margin there.

Perhaps that sounded negative, but there is still reason to be glad,
becuse from my own tests I can see that SVN can saturate a 2 Mbit link
without even breaking a sweat. That means that it is fast enough for a
lot of Internet applications, and at least to me, that is great news!


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Received on Tue Oct 28 01:44:42 2003

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