mmap002 execution time doubled... good or bad sign?

mmap002 execution time doubled... good or bad sign?

[Roger Larsson]

Hi,

I have been running various stress tests on disk for some time.
streaming write, copy, read, diff, dbench and mmap002

This is what I have seen:

>From 2.4.0 to 2.4.1 with Marcelos patch write were above 10 MB/s
and read >13 MB/s, dbench > 10 MB/s, mmap took around 2m30.

After 2.4.1-pre8 (did not test anything in between)
Write is at 9-10 [lost 1 MB/s] read is down to 11-12 MB/s [lost 2 MB/s]
dbench > 9 MB/s [one MB/s there too]

But the really strange one - mmap002 now takes > 4m30
Is this expected / good behaviour? mmap002 abuses mmaps...

/RogerL

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Re: mmap002 execution time doubled... good or bad sign?

[Marcelo Tosatti]

On Sat, 10 Feb 2001, Roger Larsson wrote:

> Hi,
> 
> I have been running various stress tests on disk for some time.
> streaming write, copy, read, diff, dbench and mmap002
> 
> This is what I have seen:
> 
> >From 2.4.0 to 2.4.1 with Marcelos patch write were above 10 MB/s
> and read >13 MB/s, dbench > 10 MB/s, mmap took around 2m30.
> 
> After 2.4.1-pre8 (did not test anything in between)
> Write is at 9-10 [lost 1 MB/s] read is down to 11-12 MB/s [lost 2 MB/s]
> dbench > 9 MB/s [one MB/s there too]
> 
> But the really strange one - mmap002 now takes > 4m30
> Is this expected / good behaviour? mmap002 abuses mmaps...

These are probably Jens modifications to the block queuing mechanisms
since there were no VM changes from 2.4.1-pre8 to now in Linus tree.

Its not necessarily a bad thing, since Jens modifications make processes
throttle on IO sooner. 

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