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From: Alexey Dobriyan <adobriyan@gmail.com>
To: jeffm@suse.com
Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	Al Viro <viro@zeniv.linux.org.uk>,
	"Eric W . Biederman" <ebiederm@xmission.com>,
	Oleg Nesterov <oleg@redhat.com>
Subject: Re: [RFC] [PATCH 0/5] procfs: reduce duplication by using symlinks
Date: Tue, 24 Apr 2018 09:17:00 +0300	[thread overview]
Message-ID: <20180424061700.GA3689@avx2> (raw)
In-Reply-To: <20180424022106.16952-1-jeffm@suse.com>

On Mon, Apr 23, 2018 at 10:21:01PM -0400, jeffm@suse.com wrote:
> Memory pressure isn't really an issue on this machine, so we
> end up using well over 100GB for proc files.

Text files at scale!

> With these patches applied, running the same testcase, the proc_inode
> cache only gets to about 600k objects, which is about 99.7% fewer.  I
> get that procfs isn't supposed to be scalable, but this is kind of
> extreme. :)

Easy stuff:
* all ->get_link hooks are broken in RCU lookup (use GFP_KERNEL),
* "%.*s" for dentry names is probably unnecessary,
  they're always NUL terminated
* kasprintf() does printing twice, since we're kind of care about /proc
  performance, allocate for the worst case.

* "int nlinks = nlink_tgid;"
  Unsigned police.

* (inode->i_mode & S_IFLNK)
	this is sketchy, S_ISLNK exists.

  parent reply	other threads:[~2018-04-24  6:17 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-24  2:21 jeffm
2018-04-24  2:21 ` [PATCH 1/5] procfs: factor out a few helpers jeffm
2018-04-24  2:21 ` [PATCH 2/5] procfs: factor out inode revalidation work from pid_revalidation jeffm
2018-04-24  2:21 ` [PATCH 3/5] procfs: use symlinks for /proc/<pid>/task when not thread group leader jeffm
2018-04-24  2:21 ` [PATCH 4/5] procfs: share common directories between /proc/tgid and /proc/tgid/task/tgid jeffm
2018-04-24  2:21 ` [PATCH 5/5] procfs: share fd/fdinfo with thread group leader when files are shared jeffm
2018-04-24 15:41   ` kbuild test robot
2018-04-24 15:41   ` [RFC PATCH] procfs: proc_pid_files_link_dentry_operations can be static kbuild test robot
2018-04-24  6:17 ` Alexey Dobriyan [this message]
2018-04-25 18:04   ` [RFC] [PATCH 0/5] procfs: reduce duplication by using symlinks Jeff Mahoney
2018-04-24 14:14 ` Eric W. Biederman
2018-04-26 21:03   ` Jeff Mahoney
2019-03-21 18:30   ` Jeff Mahoney
2019-03-23 15:56     ` Eric W. Biederman
2019-03-24  3:01       ` Jeff Mahoney

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