Messages in this thread | | | Date | Sat, 13 Nov 1999 21:00:52 +0100 | From | Manfred Spraul <> | Subject | Re: [Patch] shm bug introduced with pagecache in 2.3.11 |
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Dominik Kubla wrote: > Gerard was referring to the source code of the _OS_, not your benchmark! > And i have to agree with him: There is no way to understand what a OS > is really doing without looking at the source.
In this case you don't need the source code: Do you have a really noisy drive with a slow seek time? Then you would hear the difference: - WinNT and Linux-fork sound 'round' with lots of threads/processes, and the performance increases.
- Linux-multithread always sounds identical (1 thread or 64); the performance doesn't change.
You don't need to be a rocket scientist to figure out that the cause is the mmap semaphore, ie that Linux single threads the io for multi-threaded applications. Linux with multiple processes or WinNT reorder the disk io, and thus they get faster with more processes/threads.
-- Manfred P.S.: if you prefer to look at the source, then compare Linux-fork and Linux-multithread.
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