On Tue, Jun 14, 2005 at 01:03:38PM -0700, Andrew Morton wrote:
> Dipankar Sarma <[email protected]> wrote:
> >
> > tiobench on a 4-way ppc64 system :
> > (lockfree)
> > Test 2.6.10-vanilla Stdev 2.6.10-fd Stdev
> > -------------------------------------------------------------
> > Seqread 1428 32.47 1475.0 29.11
> > Randread 1469.2 17.27 1599.6 35.95
> > Seqwrite 262.06 9.31 246.8 30.94
> > Randwrite 548.38 12.49 521.4 61.98
>
> We don't seem to have gained anything?
Look at the read numbers - lockfree is statistically better. The
write numbers varied just too much to mean anything. Besides, this
is on ppc64, with LL/SC type of lock. Here are the x86 numbers -
tiobench on a 4(8)-way (HT) P4 system on ramdisk :
(lockfree)
Test 2.6.10-vanilla Stdev 2.6.10-fd Stdev
-------------------------------------------------------------
Seqread 1400.8 11.52 1465.4 34.27
Randread 1594 8.86 2397.2 29.21
Seqwrite 242.72 3.47 238.46 6.53
Randwrite 445.74 9.15 446.4 9.75
The performance improvement is very significant.
We are getting killed by the cacheline bouncing of the files_struct
lock here. Writes on ramdisk (ext2) seems to vary just too
much to get any meaningful number.
Also, With Tridge's thread_perf test on a 4(8)-way (HT) P4 xeon system :
2.6.12-rc5-vanilla :
Running test 'readwrite' with 8 tasks
Threads 0.34 +/- 0.01 seconds
Processes 0.16 +/- 0.00 seconds
2.6.12-rc5-fd :
Running test 'readwrite' with 8 tasks
Threads 0.17 +/- 0.02 seconds
Processes 0.17 +/- 0.02 seconds
Thanks
Dipankar
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