Re: Improving prep_buildtree used in VPATH builds

From: Alvaro Herrera <alvherre(at)commandprompt(dot)com>
To: Gurjeet Singh <singh(dot)gurjeet(at)gmail(dot)com>
Cc: PGSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Improving prep_buildtree used in VPATH builds
Date: 2010-09-27 15:28:30
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Excerpts from Gurjeet Singh's message of dom sep 26 22:15:59 -0400 2010:

> Currently I am seeing a performance improvement of this script by only about
> 500 ms; say 11.8 seconds vs. 11.3 secs. But I remember distinctly that
> yesterday I was able to see an improvement of 11% on the same virtual
> machine, averaged on multiple runs; 42 sec vs 37 sec. It might be the case
> that the host OS or my Linux virtual machine were loaded at that time and
> the filesystem could not cache enough inodes.

Hmm. On my otherwise idle desktop machine, I can't measure a difference.
But this machine has enough RAM for inode cache.

With patch:

real 0m3.092s
user 0m0.900s
sys 0m2.220s

real 0m3.116s
user 0m0.928s
sys 0m2.176s

real 0m3.128s
user 0m1.040s
sys 0m2.108s

Without patch:

real 0m3.109s
user 0m0.852s
sys 0m2.180s

real 0m3.101s
user 0m0.884s
sys 0m2.264s

real 0m3.121s
user 0m0.968s
sys 0m2.140s

> Seems like it would improve performance in general, but more so under load
> conditions when you actually need it. I am not sure if -depth option is
> supported by all incarnations of 'find'.

Álvaro Herrera <alvherre(at)commandprompt(dot)com>
The PostgreSQL Company - Command Prompt, Inc.
PostgreSQL Replication, Consulting, Custom Development, 24x7 support

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