Messages in this thread | | | Date | Thu, 24 Aug 2000 00:45:54 +0200 | From | Jens Axboe <> | Subject | Re: ll_rw_blk.c fails to merge requests. Help! |
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On Wed, Aug 23 2000, Giuliano Pochini wrote: > MF means: failed to merge block xxx length yyy > REQ: got new request entry > NOREQ: failed to get new request entry and go to sleep > ADD: block xxx length yyy added (not merged) to the queue
Are you logging the _reason_ that the buffer is not being merged? Simply saying it's not merged is a bit rough, it would be nice to know why the elevator couldn't/wouldn't merge it. Also, have you looked into how the elevator works and when/why it deliberately doesn't merge buffers?
> Problems begin here: block 130972/4 cannot be merged and the list if full. > > Aug 19 22:17:21 Jay kernel: MF 130972 4 > Aug 19 22:17:21 Jay kernel: NOREQ 130972 ---+
You will only see the noreq case, when the elevator has already tried and merged the block (it would make no sense to block waiting for a free request slot, if the buffer could have been merged) and either found that no matches were found, or that coalescing should not be done because of latency considerations.
-- * Jens Axboe <axboe@suse.de> * SuSE Labs - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/
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