lkml.org 
[lkml]   [2009]   [Apr]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] blktrace: move trace/ dir to /sys/block/sda/
From
Date
On Mon, 2009-04-13 at 22:11 +0200, Ingo Molnar wrote:
> * Jens Axboe <jens.axboe@oracle.com> wrote:
>
> > On Mon, Apr 13 2009, Li Zefan wrote:
> > > Impact: allow ftrace-plugin blktrace to trace device-mapper devices
> > >
> > > blktrace can't trace a single partition, so it makes no sense to
> > > have one trace/ dir in each /sys/block/sda/sdaX. Move it to
> > > /sys/block/sda/.
> > >
> > > Thus we fix an issue reported by Ted, that ftrace-plugin
> > > blktrace can't be used to trace device-mapper devices.
> >
> > Perhaps I never committed that patch, but it would be trivial to
> > do partition based blktrace tracing. It's also quite useful. So
> > please don't go changing things to make that harder to support, it
> > would be nicer to just add the (small) bits to support
> > per-partition tracing. It's basically just a start/stop sector
> > range, while some events are per-device and should just be
> > included always.
>
> btw., per tracepoint filters could be used for that. That would
> allow multiple partitions to be traced at once.
>
> blktrace user-space could make use of sector range filters straight
> away [ hm, Tom - do we have the <= comparison operator already, or
> is that still WIP? ] - but i think it's better to do this in a more

The new comparison operators aren't there yet, but will be part of the
new parser, which I'll be getting back to this week.

Tom

> integrated way: via the sysfs API, via /sys/block/sda/sda2/trace/.
>
> So when a partition's trace entry is activated, it would
> auto-install a specific filter expression for sda, with the sector
> range of that partition. Or something like that. How does this
> sound?
>
> Ingo



\
 
 \ /
  Last update: 2009-04-14 06:17    [from the cache]
©2003-2014 Jasper Spaans. Advertise on this site