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Re: [Jfs-discussion] benchmark results

To: Larry McVoy <lm@xxxxxxxxxxxx>
Subject: Re: [Jfs-discussion] benchmark results
From: Christian Kujau <lists@xxxxxxxxxxxxxxx>
Date: Fri, 25 Dec 2009 10:51:05 -0800 (PST)
Cc: tytso@xxxxxxx, jfs-discussion@xxxxxxxxxxxxxxxxxxxxx, linux-nilfs@xxxxxxxxxxxxxxx, xfs@xxxxxxxxxxx, reiserfs-devel@xxxxxxxxxxxxxxx, Peter Grandi <pg_jf2@xxxxxxxxxxxxxxxxxx>, ext-users <ext3-users@xxxxxxxxxx>, linux-ext4@xxxxxxxxxxxxxxx, linux-btrfs@xxxxxxxxxxxxxxx
In-reply-to: <20091225162238.GB19303@xxxxxxxxxxxx>
References: <alpine.DEB.2.01.0912240205510.3483@xxxxxxxxxxxxxxxxxx> <19251.26403.762180.228181@xxxxxxxxxxxxxxxxxx> <20091224212756.GM21594@xxxxxxxxx> <alpine.DEB.2.01.0912241739160.3483@xxxxxxxxxxxxxxxxxx> <20091225161453.GD32757@xxxxxxxxx> <20091225162238.GB19303@xxxxxxxxxxxx>
User-agent: Alpine 2.01 (DEB 1266 2009-07-14)
On Fri, 25 Dec 2009 at 08:22, Larry McVoy wrote:
> Dudes, sync() doesn't flush the fs cache, you have to unmount for that.

Thanks Larry, that was exactly my point[0] too, I should add that to the 
results page to avoid further confusion or misassumptions:

   > Well, I do "sync" after each operation, so the data should be on
   > disk, but that doesn't mean it'll clear the filesystem buffers 
   > - but this doesn't happen that often in the real world too.

I realize however that on the same results page the bonnie++ tests were 
run with a filesize *specifically* set to not utilize the filesystem 
buffers any more but the measure *disk* performance while my "generic* 
tests do something else - and thus cannot be compared to the bonnie++ or 
hdparm results.

> No idea if that is still supported, but sync() is a joke for benchmarking.

I was using "sync" to make sure that the data "should" be on the disks 
now, I did not want to flush the filesystem buffers during the "generic" 


[0] http://www.spinics.net/lists/linux-ext4/msg16878.html
BOFH excuse #210:

We didn't pay the Internet bill and it's been cut off.

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