Messages in this thread | | | Subject | Re: [PATCH V5 00/11] blktrace: output cgroup info | From | Jens Axboe <> | Date | Wed, 12 Jul 2017 16:50:55 -0600 |
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On 07/12/2017 12:49 PM, Shaohua Li wrote: > From: Shaohua Li <shli@fb.com> > > Hi, > > Currently blktrace isn't cgroup aware. blktrace prints out task name of current > context, but the task of current context isn't always in the cgroup where the > BIO comes from. We can't use task name to find out IO cgroup. For example, > Writeback BIOs always comes from flusher thread but the BIOs are for different > blk cgroups. Request could be requeued and dispatched from completely different > tasks. MD/DM are another examples. This brings challenges if we want to use > blktrace for performance tunning with cgroup enabled. > > This patchset try to fix the gap. We print out cgroup fhandle info in blktrace. > Userspace can use open_by_handle_at() syscall to find the cgroup by fhandle. Or > userspace can use name_to_handle_at() syscall to find fhandle for a cgroup and > use a BPF program to filter out blktrace for a specific cgroup. > > The first 6 patches adds export operation handlers for kernfs, so userspace can > use open_by_handle_at/name_to_handle_at to a kernfs file. Later patches make > blktrace output cgroup info.
Added for 4.14, thanks Shaohua.
-- Jens Axboe
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