From: "Serge E. Hallyn" <serge@hallyn.com>
To: Tejun Heo <tj@kernel.org>
Cc: "Serge E. Hallyn" <serge@hallyn.com>,
gregkh@linuxfoundation.org, serge.hallyn@ubuntu.com,
linux-kernel@vger.kernel.org, cgroups@vger.kernel.org,
kernel-team@fb.com, hannes@cmpxchg.org, lizefan@huawei.com
Subject: Re: [PATCH 2/4] kernfs: make kernfs_path*() behave in the style of strlcpy()
Date: Tue, 9 Aug 2016 15:14:41 -0500 [thread overview]
Message-ID: <20160809201441.GA2513@mail.hallyn.com> (raw)
In-Reply-To: <20160809195813.GF4906@mtj.duckdns.org>
Quoting Tejun Heo (tj@kernel.org):
> Hello, Serge.
>
> On Tue, Aug 09, 2016 at 10:33:05AM -0500, Serge E. Hallyn wrote:
> > > + for (i = depth_to - 1; i >= 0; i--) {
> > > + for (kn = kn_to, j = 0; j < i; j++)
> > > + kn = kn->parent;
> >
> > This is O(n^2) where n is the path depth. It's not a hot path, though, do
> > we care?
>
> I don't think it matters. It's a slow path and cgroup hierarchies
> aren't supposed to be super deep to begin with. If it ever does, we
> can replace the cgroup->ancestor_ids[] array with ancestor pointer
> array and walk that instead.
>
> Thanks.
Ok, thanks
Acked-by: Serge Hallyn <serge@hallyn.com>
next prev parent reply other threads:[~2016-08-09 20:14 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-09 5:23 [PATCHSET] kernfs, cgroup: make kernfs_path*() and cgroup_path*() behave in strlcpy() style Tejun Heo
2016-08-09 5:23 ` [PATCH 1/4] kernfs: add dummy implementation of kernfs_path_from_node() Tejun Heo
2016-08-09 6:14 ` [PATCH v2 " Tejun Heo
2016-08-09 5:23 ` [PATCH 2/4] kernfs: make kernfs_path*() behave in the style of strlcpy() Tejun Heo
2016-08-09 15:33 ` Serge E. Hallyn
2016-08-09 19:58 ` Tejun Heo
2016-08-09 20:14 ` Serge E. Hallyn [this message]
2016-08-09 5:23 ` [PATCH 3/4] kernfs: remove kernfs_path_len() Tejun Heo
2016-08-09 5:23 ` [PATCH 4/4] cgroup: make cgroup_path() and friends behave in the style of strlcpy() Tejun Heo
2016-08-09 6:14 ` [PATCH v2 " Tejun Heo
2016-08-09 8:18 ` [PATCHSET] kernfs, cgroup: make kernfs_path*() and cgroup_path*() behave in strlcpy() style Greg KH
2016-08-10 15:25 ` Tejun Heo
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