Messages in this thread | | | Date | Wed, 7 Jan 2009 16:45:17 +0100 | From | Jan Kara <> | Subject | Increase dirty_ratio and dirty_background_ratio? |
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Hi,
I'm writing mainly to gather opinions of clever people here ;). In commit 07db59bd6b0f279c31044cba6787344f63be87ea (in April 2007) Linus has decreased default /proc/sys/vm/dirty_ratio from 40 to 10 and /proc/sys/vm/dirty_background_ratio from 10 to 5. While tracking performance regressions in SLES11 wrt SLES10 we noted that this has severely affected perfomance of some workloads using Berkeley DB (basically because what the database does is that it creates a file almost as big as available memory, mmaps it and randomly scribbles all over it and with lower limits it gets much earlier throttled / pdflush is more aggressive writing back stuff which is counterproductive in this particular case). So the question is: What kind of workloads are lower limits supposed to help? Desktop? Has anybody reported that they actually help? I'm asking because we are probably going to increase limits to the old values for SLES11 if we don't see serious negative impact on other workloads... Thanks for any ideas.
Honza -- Jan Kara <jack@suse.cz> SUSE Labs, CR
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