All of lore.kernel.org
 help / color / mirror / Atom feed
From: Tejun Heo <tj@kernel.org>
To: Namhyung Kim <namhyung@kernel.org>
Cc: Song Liu <liu.song.a23@gmail.com>, Ingo Molnar <mingo@kernel.org>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	LKML <linux-kernel@vger.kernel.org>, Jiri Olsa <jolsa@redhat.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Stephane Eranian <eranian@google.com>,
	Li Zefan <lizefan@huawei.com>,
	Johannes Weiner <hannes@cmpxchg.org>
Subject: Re: [PATCH 2/9] perf/core: Add PERF_SAMPLE_CGROUP feature
Date: Mon, 7 Oct 2019 07:16:51 -0700	[thread overview]
Message-ID: <20191007141651.GE3404308@devbig004.ftw2.facebook.com> (raw)
In-Reply-To: <CAM9d7cjbt6TYL_uiwu9DSiJLW-nx3P=BpWvqu-pR=DNSD2Dzdg@mail.gmail.com>

Hello,

On Wed, Oct 02, 2019 at 03:28:00PM +0900, Namhyung Kim wrote:
> On Sat, Sep 21, 2019 at 6:04 AM Tejun Heo <tj@kernel.org> wrote:
> >
> > On Fri, Sep 20, 2019 at 05:47:45PM +0900, Namhyung Kim wrote:
> > > Thanks for the sharing information!  For 32-bit, while the ino itself is not
> > > monotonic, gen << 32 + ino is monotonic right?  I think we can use the
> >
> > It's not.  gen gets incremented on every allocation, so it has not
> > high but still realistic chance of collisions.
> 
> In __kernfs_new_node(), gen gets increased only if idr_alloc_cyclic()
> returns lower than the cursor...  I'm not sure you talked about it.

Ah, I forgot that it's using cyclic idr, so yeah, it's not as bad in
terms of recycling although cyclic allocation on idr is pretty
inefficient.  I still think it'd be better to switch to rbtree and so
that 64bit can simply use monotonically increasing numbers but that
definitely isn't a must and we can juse continue with the current
allocation method.

Thanks.

-- 
tejun

  reply	other threads:[~2019-10-07 14:16 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-28  7:31 [PATCHSET 0/9] perf: Improve cgroup profiling (v1) Namhyung Kim
2019-08-28  7:31 ` [PATCH 1/9] perf/core: Add PERF_RECORD_CGROUP event Namhyung Kim
2019-08-28  9:44   ` Peter Zijlstra
2019-08-28  9:44   ` Peter Zijlstra
2019-08-28 13:13     ` Arnaldo Carvalho de Melo
2019-08-30  3:46     ` Namhyung Kim
2019-08-30  7:34       ` Peter Zijlstra
2019-08-30 22:49         ` Namhyung Kim
2019-08-30 23:52           ` Stephane Eranian
2019-08-28 14:48   ` Tejun Heo
2019-08-30  3:56     ` Namhyung Kim
2019-08-28  7:31 ` [PATCH 2/9] perf/core: Add PERF_SAMPLE_CGROUP feature Namhyung Kim
2019-08-28 14:49   ` Tejun Heo
2019-08-31  3:03     ` Namhyung Kim
2019-08-31  4:58       ` Tejun Heo
2019-09-03  2:13         ` Namhyung Kim
2019-09-05 16:56           ` Tejun Heo
2019-09-08 13:28             ` Namhyung Kim
2019-09-14 14:02         ` Song Liu
2019-09-16 15:23           ` Tejun Heo
2019-09-19  6:42             ` Song Liu
2019-09-20  8:47               ` Namhyung Kim
2019-09-20 16:13                 ` Song Liu
2019-09-20 21:04                 ` Tejun Heo
2019-10-02  6:28                   ` Namhyung Kim
2019-10-07 14:16                     ` Tejun Heo [this message]
2019-08-28  7:31 ` [PATCH 3/9] perf tools: Basic support for CGROUP event Namhyung Kim
2019-08-30 12:55   ` Arnaldo Carvalho de Melo
2019-08-30 22:51     ` Namhyung Kim
2019-08-28  7:31 ` [PATCH 4/9] perf tools: Maintain cgroup hierarchy Namhyung Kim
2019-08-28  7:31 ` [PATCH 5/9] perf report: Add 'cgroup' sort key Namhyung Kim
2019-08-28  7:31 ` [PATCH 6/9] perf record: Support synthesizing cgroup events Namhyung Kim
2019-08-28  7:31 ` [PATCH 7/9] perf record: Add --all-cgroups option Namhyung Kim
2019-08-28  7:31 ` [PATCH 8/9] perf top: " Namhyung Kim
2019-08-28  7:31 ` [PATCH 9/9] perf script: Add --show-cgroup-events option Namhyung Kim
2019-12-20  4:32 [PATCHSET 0/9] perf: Improve cgroup profiling (v2) Namhyung Kim
2019-12-20  4:32 ` [PATCH 2/9] perf/core: Add PERF_SAMPLE_CGROUP feature Namhyung Kim
2019-12-20  9:36   ` Peter Zijlstra
2019-12-20 15:23   ` Tejun Heo
2019-12-20 16:48     ` Peter Zijlstra
2019-12-20 16:59       ` Tejun Heo
2019-12-23  6:07 [PATCHSET 0/9] perf: Improve cgroup profiling (v3) Namhyung Kim
2019-12-23  6:07 ` [PATCH 2/9] perf/core: Add PERF_SAMPLE_CGROUP feature Namhyung Kim
2020-01-07 13:34 [PATCHSET 0/9] perf: Improve cgroup profiling (v4) Namhyung Kim
2020-01-07 13:34 ` [PATCH 2/9] perf/core: Add PERF_SAMPLE_CGROUP feature Namhyung Kim
2020-03-25 12:45 [PATCHSET 0/9] perf: Improve cgroup profiling (v6) Namhyung Kim
2020-03-25 12:45 ` [PATCH 2/9] perf/core: Add PERF_SAMPLE_CGROUP feature Namhyung Kim

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20191007141651.GE3404308@devbig004.ftw2.facebook.com \
    --to=tj@kernel.org \
    --cc=a.p.zijlstra@chello.nl \
    --cc=acme@kernel.org \
    --cc=alexander.shishkin@linux.intel.com \
    --cc=eranian@google.com \
    --cc=hannes@cmpxchg.org \
    --cc=jolsa@redhat.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=liu.song.a23@gmail.com \
    --cc=lizefan@huawei.com \
    --cc=mingo@kernel.org \
    --cc=namhyung@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.