Re: [Patch] shm bug introduced with pagecache in 2.3.11

Manfred Spraul (manfreds@colorfullife.com)
Sat, 13 Nov 1999 02:09:25 +0100

Linus Torvalds wrote:
>
> > Btw, I'm sure that for multi-threaded applications, the mmap performance
> > of Linux will be poor because everything is single-threaded. I'll
> > write a benchmark and compare it with WinNT/Win95.
>
> I will bet you 5 bucks we'll kick ass.
>
You've lost:

Computer: K6-200, 128 MB Ram, Symbios 810 scsi controller, Fujitsu
Magneto-Optical drive, 620 MB [I have no empty scsi disc left :(],
620,000,000 bytes test file, fat filesystem, the same disk is used for
NT and Linux.

command: "./pagein fill 150000 #" where fill is the filename, 150000
means 150000 pages are trashed, and # is the number of threads.

Linux:
# pages/sec
1 13
4 14
64 14
256 ? [computer unresponsive]

NT:
# pages/sec
1 18
4 20
64 28
256 31
512 33

Linux is slower, and it cannot use multiple threads to reorder the
sector reads;
NT gets faster if I add further threads.

source code is at
http://colorfullife.com/~manfreds/pagein/pagein.cpp

--
	Manfred




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