Re: dentry bloat.
From: Dipankar Sarma
Date: Fri May 14 2004 - 06:46:41 EST
On Fri, May 14, 2004 at 04:03:23PM +0530, Raghavan wrote:
> Environment - 2-way P4 Xeon 2.4MHz SMP box with 4.5GB RAM.
> Tests were run for 10 iterations to calculate the milliseconds/iteration
> and then mean and deviation were calculated.
I think it is microseconds/iteration. Lesser the better.
> Kernel version Mean Standard Deviation
> --------------- ---- ------------------
> 2.6.6-rc3(baseline) 10578 221
> 2.6.6 10280 110
So alignment changes helped.
> 2.6.6-bk 10862 30
Hash function changes regressed.
> 2.6.6-mm1 10626 36
dentry size change patchset helps.
> To find out if the huge performance dip between the 2.6.6
> and 2.6.6-bk is because of the hash changes, I removed the hash patch
> from 2.6.6-bk and applied it to 2.6.6.
> 2.6.6-bk with old hash 10685 34
> 2.6.6 with new hash 10496 125
> Looks like the new hashing function has brought down the performance.
> Also some code outside dcache.c and inode.c seems to have pushed down
> the performance in 2.6.6-bk.
OK, I am confused. These numbers show that the new hash function
is better. It contradicts your conclusion. And why are you
comparing 2.6.6-bk+old has with 2.6.6+new hash ? Why not
2.6.6-bk vs. 2.6.6-bk-with-old-hash ?
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