Re: ext3 performance inconsistencies, 2.4/2.6

[Linus Torvalds]

On Tue, 4 Nov 2003, Bill Rugolsky Jr. wrote:
> 
> Unless bonnie++ is using the _unlocked() variants, it might be an issue of
> the mutex overhead from NPTL v. LinuxThreads.  Red Hat 9 has its share
> of NPTL bugs.

Hmm.. That would easily explain the differences, since NPTL will trigger 
both on 2.6.0 and the RH-2.4 kernel, but not on the standard 2.4.22 
kernel.

But there really should be zero contention on the stdio data structures, 
so the locking would have to be _seriously_ broken to make that kind o 
fdifference (not necessarily buggy, but seriously badly implemented). 

A non-contended lock should be at most one locked instruction if well 
done, both on LinuxThreads and NPTL.

> It is probably worth rerunning the tests with LD_ASSUME_KERNEL=2.4.1 on
> the Red Hat kernel.

That would be interesting.

		Linus

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