>Andrew Morton wrote:
>So. Patch is a huge win as-is. For the PIII it looks like we need
>to enable it at all alignments except mod32. And we need to test
>with aligned dest, unaligned source.
Pentium III (coppermine) 997Mhz 2-way
Read from pagecache to user buffer misaligning the source
Size of copy is 262144 and the number of iterations copied for
each test is 16384.
Patch++ - uses copy_user_int if size > 64
Patch - uses copy_user_int if size > 64, or src and dst
are not aligned on an 8 byte boundary
dst aligned on an 4k and src misaligned
2.5.40 2.5.40+patch 2.5.40+patch++
Align throughout throughput throughput
(bytes) KB/sec KB/sec KB/sec
0 275592 281356 285567
1 124266 197361
2 120157 200270
4 125935 197558
8 157244 156655 162189
16 167296 173202 173702
32 283731 285222 290810
Looks like the patch can be used for all the above tested
alignments on Pentium III.
>Can you please do some P4 testing?
P4 Xeon CPU 1.50 GHz 4-way - hyperthreading disabled
Src is aligned and dst is misaligned as follows:
Dst 2.5.40 2.5.40+patch 2.5.40+patch++
Align throughout throughput throughput
(bytes) KB/sec KB/sec KB/sec
0 1360071 1314783 912359
1 323674 340447
2 329202 336425
4 512955 693170
8 523223 615097 506641
12 517184 558701 553700
16 966598 872080 932736
32 846937 838514 845178
I see too much variance in the test results so I ran
each test 3 times. I tried increasing the iterations
but it did not reduce the variance.
Dst is aligned and src is misaligned as follows:
Dst 2.5.40 2.5.40+patch
Align throughout throughput
(bytes) KB/sec KB/sec
0 1275372 1029815
1 529907 511815
2 534811 530850
4 643196 627013
8 568000 626676
12 574468 658793
16 631707 635979
32 741485 592938
Since there is 5 - 10% variance in these test's results I am not
sure whether we can use this data to validate. I will try
to run this on another pentium 4 machine.
However I have seen using floating point registers instead of integer
registers on Pentium IV improves performance to a greater extent on
some alignments. I need to do more testing and then I will create a
patch for pentium IV.
Regards,
Mala
Mala Anand
IBM Linux Technology Center - Kernel Performance
E-mail:manand@us.ibm.com
http://www-124.ibm.com/developerworks/opensource/linuxperf
http://www-124.ibm.com/developerworks/projects/linuxperf
Phone:838-8088; Tie-line:678-8088
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This archive was generated by hypermail 2b29 : Tue Oct 15 2002 - 22:00:34 EST