Re: ext3 performance inconsistencies, 2.4/2.6

[Bill Rugolsky Jr.]

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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