Messages in this thread | | | From | Heinz Mauelshagen <> | Subject | Re: Linux-2.2.0 bad VM behaviour "dd if=/dev/zero of=/dev/hdc bs=256k" | Date | Fri, 05 Feb 1999 17:28:27 MET |
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After thinking about refile_buffer and wakeup conditions for bdflush for a while i came to the following solution.
It takes care of a fixed minimum of free buffers in the buffer cache.
I hard coded 5% just for testing purposes.
if (nr_buffers_type[BUF_DIRTY] > too_many || nr_buffers - nr_buffers_type[BUF_DIRTY] - nr_buffers_type[BUF_LOCKED] < nr_buffers_type[BUF_DIRTY] / 20) wakeup_bdflush(1);
Performance is even better now while doing a "dd if=/dev/zero of=/dev/v/l bs=1024k" on a 13G device i'm able to perform a compile in 25s vs 1:20m!
Sure, if we have a reserved amount of buffers, it should be dynamically dimensioned based on load scenarios.
This is just a quick hack to show the basic idea...
Opinions?
Regards, Heinz
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Systemmanagement C/S Deutsche Telekom AG Entwicklungszentrum Darmstadt Heinz Mauelshagen Otto-Roehm-Strasse 71c Senior Systems Engineer Postfach 10 05 41 64205 Darmstadt mge@ez-darmstadt.telekom.de Germany +49 6151 886-425 FAX-386 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
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