Messages in this thread | | | From | "Stephen C. Tweedie" <> | Date | Thu, 3 Feb 2000 17:16:15 +0000 (GMT) | Subject | RE: patch: ll_rw_blk fixes |
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Hi,
On Fri, 28 Jan 2000 13:00:22 +0100, Serge Robyns <serge.robyns@advalvas.be> said:
> Is any of the active workers on the ll_rw_blk code thinking of > implementing per proces io metrics for block devices?
What sort of metrics had you in mind? In general it's pretty hard to account IO to specific processes. Write is hardest: filesystem write IO is usually triggered by the background flush services in the VM, not by the processes writing to the files in the first place. Even for reads, if several processes try to read the same data at the same time, the kernel will bring it into cache only once: who do you account the IO against?
Buffer/page cache metrics would be easier to track than actual IO: the number of buffers dirtied and the cache hit/miss rates would all be fairly easy to track.
--Stephen
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