From: Miklos Szeredi <miklos@szeredi.hu>
To: Ian Kent <raven@themaw.net>
Cc: Christian Brauner <brauner@kernel.org>,
linux-fsdevel@vger.kernel.org, Dave Chinner <david@fromorbit.com>,
"Theodore Ts'o" <tytso@mit.edu>, Karel Zak <kzak@redhat.com>,
Greg KH <gregkh@linuxfoundation.org>,
linux-kernel@vger.kernel.org,
Linux API <linux-api@vger.kernel.org>,
linux-man <linux-man@vger.kernel.org>,
LSM <linux-security-module@vger.kernel.org>,
David Howells <dhowells@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Al Viro <viro@zeniv.linux.org.uk>,
Christian Brauner <christian@brauner.io>,
Amir Goldstein <amir73il@gmail.com>,
James Bottomley <James.Bottomley@hansenpartnership.com>
Subject: Re: [RFC PATCH] getting misc stats/attributes via xattr API
Date: Tue, 10 May 2022 10:07:55 +0200 [thread overview]
Message-ID: <CAJfpegutUQOTa71NTy_iaz5Kus2ma16ALqrHtvV2+cQ0tFiaxA@mail.gmail.com> (raw)
In-Reply-To: <CAJfpegv3MCHMzur9R+K+yZC3Z_Wmbq3=pQwuQ=+kQSrihg0c9g@mail.gmail.com>
On Tue, 10 May 2022 at 10:06, Miklos Szeredi <miklos@szeredi.hu> wrote:
>
> On Tue, 10 May 2022 at 06:27, Ian Kent <raven@themaw.net> wrote:
>
> > > Was there ever a test patch for systemd using fsinfo(2)? I think
> > > not.
> >
> > Mmm ... I'm hurt you didn't pay any attention to what I did on this
> > during the original fsinfo() discussions.
>
> I can't find anything related to this in my mailbox. Maybe you
> mentioned it at some point, but I have not been involved with the
> actual systemd changes. So not meant to belittle your work at all.
>
> > > Until systemd people start to reengineer the mount handing to allow
> > > for retrieving a single mount instead of the complete mount table we
> > > will never know where the performance bottleneck lies.
> >
> > We didn't need the systemd people to do this only review and contribute
> > to the pr for the change and eventually merge it.
> >
> > What I did on this showed that using fsinfo() allone about halved the
> > CPU overhead (from around 4 processes using about 80%) and once the
> > mount notifications was added too it went down to well under 10% per
> > process. The problem here was systemd is quite good at servicing events
> > and reducing event processing overhead meant more events would then be
> > processed. Utilizing the mount notifications queueing was the key to
> > improving this and that was what I was about to work on at the end.
> >
> > But everything stopped before the work was complete.
> >
> > As I said above it's been a long time since I looked at the systemd
> > work and it definitely was a WIP so "what you see is what you get"
> > at https://github.com/raven-au/systemd/commits/. It looks like the
> > place to look to get some idea of what was being done is branch
> > notifications-devel or notifications-rfc-pr. Also note that this
> > uses the libmount fsinfo() infrastrucure that was done by Karal Zak
> > (and a tiny bit by me) at the time.
>
> Looks great as a first step.
>
> What do you mean by "Utilizing the mount notifications queueing"?
>
> Do you mean batching of notifications? I think that's a very
> important issue: processing each individual notifcation may not make
> sense when there are lots of them. For example, doing ceate
> mount+remote mount in a loop a million times will result in two
s/remote/remove/
> million notification messages (with high likelyhood of queue
> overflow), but in the end the mount table will end up being the
> same...
>
> Thanks,
> Miklos
next prev parent reply other threads:[~2022-05-10 8:08 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-03 12:23 [RFC PATCH] getting misc stats/attributes via xattr API Miklos Szeredi
2022-05-03 14:39 ` Amir Goldstein
2022-05-03 14:53 ` Greg KH
2022-05-03 15:04 ` Miklos Szeredi
2022-05-03 15:14 ` Amir Goldstein
2022-05-03 16:54 ` Greg KH
2022-05-03 22:43 ` Dave Chinner
2022-05-04 7:18 ` Miklos Szeredi
2022-05-04 14:22 ` Amir Goldstein
2022-05-05 12:30 ` Karel Zak
2022-05-05 13:59 ` Miklos Szeredi
2022-05-05 23:38 ` tytso
2022-05-06 0:06 ` Amir Goldstein
2022-05-07 0:32 ` Dave Chinner
2022-05-09 12:48 ` Christian Brauner
2022-05-09 14:20 ` Amir Goldstein
2022-05-09 15:08 ` Christian Brauner
2022-05-09 17:07 ` Amir Goldstein
2022-05-09 21:42 ` Vivek Goyal
2022-05-10 3:34 ` Ian Kent
2022-05-10 0:55 ` Dave Chinner
2022-05-10 12:40 ` Christian Brauner
2022-05-11 0:42 ` Dave Chinner
2022-05-11 9:16 ` Christian Brauner
2022-05-10 12:45 ` Florian Weimer
2022-05-10 23:04 ` Dave Chinner
2022-05-10 3:49 ` Miklos Szeredi
2022-05-10 4:27 ` Ian Kent
2022-05-10 8:06 ` Miklos Szeredi
2022-05-10 8:07 ` Miklos Szeredi [this message]
2022-05-10 11:53 ` Christian Brauner
2022-05-10 13:15 ` Miklos Szeredi
2022-05-10 13:18 ` Miklos Szeredi
2022-05-10 14:19 ` Christian Brauner
2022-05-10 14:41 ` Miklos Szeredi
2022-05-10 15:30 ` Christian Brauner
2022-05-10 15:47 ` Miklos Szeredi
2022-05-10 15:53 ` Christian Brauner
2022-05-10 12:35 ` Karel Zak
2022-05-10 23:25 ` Dave Chinner
2022-05-11 8:58 ` Karel Zak
2022-11-14 9:00 ` Abel Wu
2022-11-14 12:35 ` Miklos Szeredi
2022-11-15 3:39 ` Abel Wu
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