Messages in this thread | | | Date | Sat, 28 Aug 1999 18:31:21 -0400 (EDT) | From | Donald Becker <> | Subject | Streaming disk I/O: don't use raw, limit bufs per device/partition |
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>On Mon, 23 Aug 1999, Peter Monta wrote: >> >> > I think without some buffer-cache usage limiting, or buffering disabling, >> > Linux is actually UNSUITABLE for streaming applications which do run >> > concurrently with other apps. >> >> I agree; the raw-io system will make this much more pleasant. > >Why do you think so? > >IO is IO, whether it is raw or not. And it will eat up resources from >everybody else trying to do IO. > >I think this is a case of believing in magic cures and supernatural >beings.
We solved a similar problem by limiting the buffering per device/partition to a subset of the buffer cache (75%, tunable), rather than hacking in raw devices.
This worked extremely well for our application, a parallel file system. The system had following features: Multiple disk partitions. (Note 1) Bulk I/O tended to be on just one partition at a time. Most other processes were active in partitions without bulk I/O.
Note 1: This approach has no benefit on single-partition installations. However most bulk I/O users do have multiple partitions, and typically have multiple disks.
Donald Becker
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