Re: Linux v2.4.19-rc5

Steven Cole (elenstev@mesatop.com)
01 Aug 2002 14:15:45 -0600


On Thu, 2002-08-01 at 01:14, Marcelo Tosatti wrote:
>
> On Thu, 1 Aug 2002, Jens Axboe wrote:
>
> > On Thu, Aug 01 2002, Marcelo Tosatti wrote:
> > > <akpm@zip.com.au> (02/08/01 1.663)
> > > [PATCH] disable READA
> >
> > Since -rc5 is not to be found yet, I don't know what version of this
> > made it in. Is READA just being disabled on SMP, or was it the general
> > #if 0 change that got included?
>
> Its being disabled on UP and SMP. I dont like having such readahead IO
> mode working only for UP.
>
> > I'm asking since plain disabling READA might have nasty performance
> > effects. Andrew, I bet you did some numbers on this, care to share?
>
> If thats true (the performance effects) I'll release -final with IMO not
> very coherent READA semantics :)
>
> Anyway, lets wait for the numbers.

Marcelo,

Here are some dbench numbers, from the "for what it's worth" department.
This was done with SMP kernels, on a dual p3 box, SCSI disk, ext2.
The first column is dbench clients. The numbers are throughput
in MB/sec. The 2.5.29 kernel had a few RR-supplied smp fixes.
Looks like for this limited test, 2.4.19-rc5 holds up pretty well.
I've also ran this set of tests several times on -rc5 using ext3
and data=writeback, and everything looks fine.

Steven

2.4.19-rc2 2.4.19-rc5 2.5.29

1 114.616 113.402 112.668
2 173.234 183.829 175.148
3 185.995 187.411 184.63
4 185.447 186.891 188.199
6 191.115 191.439 191.787
8 191.962 191.551 191.53
10 192.984 194.036 194.923
12 183.847 185.73 195.328
16 183.609 183.439 196.224
20 181.519 179.956 193.681
24 183.509 183.387 194.09
28 176.04 175.832 169.326
32 174.583 163.09 137.815
36 155.04 164.154 121.861
40 155.37 156.028 102.014
44 152.546 138.171 91.6088
48 146.419 135.447 84.3884
52 139.788 125.968 89.2374
56 113.933 122.592 81.021
64 110.792 106.484 84.648
80 87.4692 60.6054
96 87.7201 57.9622
112 74.9503 49.468
128 67.2649 47.0254

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