Messages in this thread | | | From | Benno Senoner <> | Date | Sun, 29 Aug 1999 02:27:23 +0200 |
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On Sun, 29 Aug 1999, Helge Hafting wrote: > > - The disk performance decreases by 10-25% when I increase the CPU load in > > the "latencytest" bench. > The server people certainly won't like that.
Nor I do. But I'm still not convinced it this is really possible. You have to check rescheduling during kernel memcopy routines , or large mem blocks moves, since at 100MB/sec 1MB of data = 10msec latency. It not an easy task to keep latencies down. Maybe the checking generates some cache misses and decreases performance, especially when copying many small blocks ?
> > > I think most of us want to have these "low-latency" features in the upcoming > > 2.4 kernel since it will make Linux a very good _MULTIMEDIA_OS_. > > Everybody wants low-latency. But Linus looked at the patches and said > "If *that* helps then something is wrong. Those functions shouldn't > take so much time!" > He then refused to accept patches that "paper over" a bug. Instead he > wanted the bug fixed (i.e. make the functions in question take less > time - they way they should.)
Agreed, but the question is: is some kernel hacker motivated to do implement this before 2.4 ?
> That would give the same low latency without hurting disk performance under > load.
I'm not 100%sure about this .. Nothing comes at zero cost..
regards, Benno.
-- Benno Senoner E-Mail: sbenno@gardena.net Linux scheduling latency benchmarks http://www.gardena.net/benno/linux/audio
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