Hi, Thanks for your reply. >>3) Use "dirty_ratio" as the blocking ratio. And add >> "start_writeback_ratio", and start writeback at >> start_writeback_ratio(default:90) * dirty_ratio / 100 [%]. >> In this way, specifying blocking ratio can be done in the same way >> as current kernel, but high/low watermark algorithm is enabled. >I like 3 better, it should make tuning behavior more precise.
Then, what do you think of the following idea? (4) add `dirty_start_writeback_ratio' as percentage of memory, at which a generator of dirty pages itself starts writeback (that is, non-blocking ratio). In this way, `dirty_ratio' is used as the blocking ratio, so we don't need to modify the sysctl.conf etc. I think it's easier to understand for administrators of systems, because the interface is similar as `dirty_background_ratio' and`dirty_ratio.' If this is OK, I'll repost the patch. > You can make an argument for absolute values for writeback, > if my disk will only write 70MB/s I may only want 203 sec of > pending writes, regardless of available memory. To realize tuning with absolute values, I consider that we need to modify handling of `dirty_background_ratio,' `dirty_ratio' and so on as well as `dirty_start_writeback_ratio.' I think this should be done in another patch if this feature is required. Regards, -- Tomoki Sekiyama Hitachi, Ltd., Systems Development Laboratory - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/