Tomoki Sekiyama wrote:
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.
It sounds good to me, just be sure behavior is sane for for both
blocking less than start_writeback and vice versa.
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
--
bill davidsen <[EMAIL PROTECTED]>
CTO TMR Associates, Inc
Doing interesting things with small computers since 1979
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