Messages in this thread | | | Date | Tue, 08 Sep 2009 10:02:38 +0800 | From | Li Zefan <> | Subject | Re: [PATCH] trace bio queueing trial only when it occurs |
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Wu Fengguang wrote: > Minchan, > > I tend to agree with the change, but somehow confused by blkparse(1): > > Q -- queued This notes *intent* to queue i/o at the given location. No real requests exists yet. > > Li Zefan has been working on blktrace and he can tell more. >
I work on ftrace-plugin blktrace and blk TRACE_EVENT, but don't know much about the old blktrace history. ;)
I think the manpage says it's called before ->make_request_fn(), so "No real requests exist yet".
Actually the trace was called just before make_request at first: 2056a782f8e7e65fd4bfd027506b4ce1c5e9ccd4
And then 2 patches added some checks between them: 5ddfe9691c91a244e8d1be597b6428fcefd58103 51fd77bd9f512ab6cc9df0733ba1caaab89eb957
It seems to me it makes sense to have this patch.
> Thanks, > Fengguang > > On Tue, Sep 08, 2009 at 08:34:16AM +0800, Minchan Kim wrote: >> It got lost in LKML mail storm. >> I resend this. >> Wu, Could you review this patch, please? >> >> == CUT_HERE == >> >> If BIO is discarded or cross over end of device, >> BIO queueing trial doesn't occur. >> >> Let's trace it only when it happens. >> >> Signed-off-by: Minchan Kim <minchan.kim@gmail.com> >> --- >> block/blk-core.c | 4 ++-- >> 1 files changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/block/blk-core.c b/block/blk-core.c >> index 5b59592..1a0cfd5 100644 >> --- a/block/blk-core.c >> +++ b/block/blk-core.c >> @@ -1463,8 +1463,6 @@ static inline void __generic_make_request(struct bio *bio) >> if (old_sector != -1) >> trace_block_remap(q, bio, old_dev, old_sector); >> >> - trace_block_bio_queue(q, bio); >> - >> old_sector = bio->bi_sector; >> old_dev = bio->bi_bdev->bd_dev; >> >> @@ -1477,6 +1475,8 @@ static inline void __generic_make_request(struct bio *bio) >> goto end_io; >> } >> >> + trace_block_bio_queue(q, bio); >> + >> ret = q->make_request_fn(q, bio); >> } while (ret); >> >> -- >> 1.6.4 >> >> >>
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