>Date: Mon, 16 Jul 2001 14:03:30 +0200 (MET DST) >From: "Maciej W. Rozycki" <macro@ds2.pg.gda.pl> >To: Ralf Baechle <ralf@oss.sgi.com> >Subject: Re: ll/sc emulation patch > >On Sat, 14 Jul 2001, Ralf Baechle wrote: > >> I'm just making an attempt to re-implement the ll/sc emulation as light >> as possible. I hope to get the overhead down to the point were we don't >> need _test_and_set anymore - in any case below the overhead of a syscall. >> >> Have you ever profiled the number of calls to MIPS_ATOMIC_SET or >> _test_and_set? They'll be the other factor in a decission. > > I didn't profile it very extensively, yet when stracing `ls /usr/lib' >(fileutils 4.1 linked against glibc 2.2.3) on my system once I yielded >~4500 syscalls of which ~4000 were _test_and_set() (or MIPS_ATOMIC_SET, >depending on my kernel/glibc configuration) invocations. Yes, libpthread >appears to assume atomic operations are cheap, which is justifiable as >they are indeed, for almost every other CPU type. Not knowing anything about the glibc architecture, I have a dumb question: why is 'ls' doing anything at all with pthreads? Mike McDonald mikemac@mikemac.com
