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RE: svn edit

From: Harvey, Edward <Edward.Harvey_at_patni.com>
Date: Tue, 28 Oct 2008 13:09:04 -0400

Incase anybody wants to benchmark anything - on Linux - I learned this from Linus.
     echo 3 >/proc/sys/vm/drop_caches
     This will make your cache cold, so you can repeat a test with accurate results. (without rebooting)

From: Harvey, Edward
Sent: Tuesday, October 28, 2008 12:49 PM
To: Branko Čibej; dev_at_subversion.tigris.org
Subject: RE: svn edit

> Just to illustrate what I mean by "optimizing WC scans" and put some
> code where my mouth is ... here's a *very* trivial example. See the
> attached script. On my box, the less_stupid scan is consistenly 30-40%
> faster (with full caches!) than the stupid one, merely because it tries
> to keep accesses slightly more local.

I'm not sure what you mean by "with full caches" or "keep access more local" but I do know this -
        I created a similar python script to walk a tree.
        With cold cache, local disk, python walking the tree on 100,000 files takes approx 10 sec
        With cold cache, local disk, "svn stat" on 17,000 files (50,000 including .svn dirs) takes approx 4 mins
        With cold cache, local disk, "git status" on 17,000 files (30,000 including .git dirs) takes approx 2 mins
        Perforce is able to do this is zero time. (a few ms)

Now - If svn is able to get anywhere near the 10 sec mark for 100,000 files, I say fine. But I seriously doubt svn will beat the performance of git by using the same strategy that git uses (walk the tree). This costs at least one order of magnitude in performance.

Put simply, as far as performance is concerned, Perforce has a strategy that beats the pants off either svn or git. Because perforce doesn't need to walk the tree.

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Received on 2008-10-28 18:12:09 CET

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