Messages in this thread | | | Date | Mon, 09 Jan 2012 11:33:27 +0900 | From | Namhyung Kim <> | Subject | Re: [PATCH 03/11] block: block_bio_complete tracepoint was missing |
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Hi,
2012-01-09 10:49 AM, Tejun Heo wrote: > Hello, > > On Mon, Jan 09, 2012 at 10:30:06AM +0900, Namhyung Kim wrote: >> Just adding the TP unconditionally will produce duplicated (in some >> sense) reports about the completion. For example, normal request >> based IO reports whole request completion prior to its bio's, and >> further > > Request and bio completions are separate events. There's nothing > wrong with reporting them separately. In fact, I think they should be > reported separately. > >> , some of nested block IO handling routines - bounced bio and >> btrfs with compression, etc - call bio_endio() more than once. Also >> there are cases that bio fails before it's enqueued for some reason. > > They are actually separate bio's being completed. I don't think > trying to put extra semantics on TP itself is a good idea. In > general, TP signals that such event happened with sufficient > information and it's the consumers' responsibility to make sense of > what's going on. BIO_CLONED/BOUNCED are there.
I see.
>> I have no idea about the ioblame can deal with all of such corner >> cases. However it might confuse blktrace somewhat, I guess. > > Unless someone is doing memcpy() on bio's, ioblame should be okay. It > only considers bio's which went through actual submission. > >> I already posted similar patch a couple of weeks ago, but didn't >> receive a comment yet. [1] Please take a look this too :) > > I'll reply there but don't think imposing such extra logic on TP is a > good idea.
I'll reply on that thread too. :)
>> After a quick glance, the ioblame seems to carry all IO accounting >> info through the first bio in the request. If so, why don't you use >> the request structure for that? > > Because there are bio based drivers which don't use requests at all.
What I thought for such drivers was dynamic allocation in their ->make_request_fn, but because we don't have a block_bio_issue TP, Nevermind. :)
Thanks, Namhyung Kim
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