Re: ext3 performance inconsistencies, 2.4/2.6

From: Jakub Jelinek
Date: Wed Nov 05 2003 - 02:09:32 EST

On Tue, Nov 04, 2003 at 07:58:16PM -0500, jlnance@xxxxxxxxxxxxxx wrote:
> On Tue, Nov 04, 2003 at 03:48:28PM -0800, Ulrich Drepper wrote:
> >
> > The first is the old nptl code, the second LinuxThreads, the third the
> > current nptl code.
> By current, do you mean what is in Fedora, or you personal development copy?

Ulrich meant glibc CVS HEAD.
For some reason, stdio locking was not using the jump around lock prefix
variant of locking:
__asm __volatile ("cmpl $0, %%gs:%P6\n\t" \
"je,pt 0f\n\t" \
"lock\n" \
"0:\tcmpxchgl %1, %2\n\t" \
"jnz _L_mutex_lock_%=\n\t" \
".subsection 1\m\t" ...
but one without the first 2 insns, so there were 2 instructions with lock
prefix in putc and similar functions even when only one thread was running.

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