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SubjectRe: ext3 performance inconsistencies, 2.4/2.6
On Tue, Nov 04, 2003 at 01:40:51PM -0800, Linus Torvalds wrote:
> On Tue, 4 Nov 2003, Bill Rugolsky Jr. wrote:
> >
> > Well, I'm too lazy to wait for a long test, but with a mere
> > 100MB file, on 1GHz P3:
> >
> > Version 1.03 ------Sequential Output------ --Sequential Input- --Random-
> > -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
> > NPTL 100M 7735 99 127068 98 63048 84 7890 98 +++++ +++ +++++ +++
> > LinuxThreads 100M 11000 99 127928 97 59075 84 11290 98 +++++ +++ +++++ +++
> >
> > So something is amiss.
>
> Ok, so NPTL locking (even in the absense of any threads and thus any
> contention) seems to be noticeably higher-overhead than the old
> LinuxThreads.
>
> 90% of the overhead of a putc()/getc() implementation these days is likely
> just locking. Even so, this implies that NPTL locking is about twice as
> expensive as the old LinuxThreads one.

On Fedora 0.95, Pentium M 1.6GHz, 2.4.22-1.2115.nptl, glibc-2.3.2-10, (NPTL 0.60),
I get:

Version 1.03 ------Sequential Output------ --Sequential Input- --Random-
-Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP
NPTL 100M 13070 100 +++++ +++ 14141 4 13099 100 +++++ +++ +++++ +++
LinuxThreads 100M 25957 100 +++++ +++ 20037 5 26777 99 +++++ +++ +++++ +++
Ugh, still there.

Bill Rugolsky
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