Messages in this thread | | | Date | Wed, 20 May 2009 00:49:58 +0900 | Subject | Re: [RFC][PATCH] convert block trace points to TRACE_EVENT() | From | FUJITA Tomonori <> |
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On Tue, 19 May 2009 09:08:41 -0400 Christoph Hellwig <hch@infradead.org> wrote:
> On Tue, May 19, 2009 at 08:59:29AM -0400, Jeff Moyer wrote: > > I'm not sure I'm comfortable with this. Having had to diagnose > > performance problems using blktrace, I find the dev_t information for > > plugs and unplugs especially interesting. Maybe we can still figure > > this out given the context in the trace, though. Can you comment on > > that? > > The problem is that right now we still allow request queues shared by > multiple gendisks, so we can't get at the gendisk. The blktrace ioctl > interface gets around that by doing the setup with an ioctl on the > block device node and storing the dev_t at that point. > > But I don't think we actually have any drivers left sharing a queue > that way, and I'd love to get rid of that for various reasons.
There are still some (e.g. drivers/block/floppy.c)? I though that we hit this when we tried to add the command filter feature though I might be wrong (I can't recall).
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