Hi,It sounds good to me, just be sure behavior is sane for for both blocking less than start_writeback and vice versa.
Thanks for your reply.
3) Use "dirty_ratio" as the blocking ratio. And addI like 3 better, it should make tuning behavior more precise.
"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.
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
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.
Hitachi, Ltd., Systems Development Laboratory