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Message-ID: <20200304175556.45dsgxumv4ubz7qy@ws.net.home>
Date: Wed, 4 Mar 2020 18:55:56 +0100
From: Karel Zak <kzak@...hat.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Ian Kent <raven@...maw.net>, Miklos Szeredi <miklos@...redi.hu>,
David Howells <dhowells@...hat.com>,
Christian Brauner <christian.brauner@...ntu.com>,
James Bottomley <James.Bottomley@...senpartnership.com>,
Steven Whitehouse <swhiteho@...hat.com>,
Miklos Szeredi <mszeredi@...hat.com>,
viro <viro@...iv.linux.org.uk>,
Christian Brauner <christian@...uner.io>,
Jann Horn <jannh@...gle.com>,
"Darrick J. Wong" <darrick.wong@...cle.com>,
Linux API <linux-api@...r.kernel.org>,
linux-fsdevel <linux-fsdevel@...r.kernel.org>,
lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 00/17] VFS: Filesystem information and notifications [ver
#17]
On Wed, Mar 04, 2020 at 05:49:13PM +0100, Greg Kroah-Hartman wrote:
> On Wed, Mar 04, 2020 at 04:22:41PM +0100, Karel Zak wrote:
> > $ strace -e openat,read,close -c ps aux
> > ...
> > % time seconds usecs/call calls errors syscall
> > ------ ----------- ----------- --------- --------- ----------------
> > 43.32 0.004190 4 987 read
> > 31.42 0.003039 3 844 4 openat
> > 25.26 0.002443 2 842 close
> > ------ ----------- ----------- --------- --------- ----------------
> > 100.00 0.009672 2673 4 total
> >
> > $ strace -e openat,read,close -c lsns
> > ...
> > % time seconds usecs/call calls errors syscall
> > ------ ----------- ----------- --------- --------- ----------------
> > 39.95 0.001567 2 593 openat
> > 30.93 0.001213 2 597 close
> > 29.12 0.001142 3 365 read
> > ------ ----------- ----------- --------- --------- ----------------
> > 100.00 0.003922 1555 total
> >
> >
> > $ strace -e openat,read,close -c lscpu
> > ...
> > % time seconds usecs/call calls errors syscall
> > ------ ----------- ----------- --------- --------- ----------------
> > 44.67 0.001480 7 189 52 openat
> > 34.77 0.001152 6 180 read
> > 20.56 0.000681 4 140 close
> > ------ ----------- ----------- --------- --------- ----------------
> > 100.00 0.003313 509 52 total
>
> As a "real-world" test, would you recommend me converting one of the
> above tools to my implementation of readfile to see how/if it actually
> makes sense, or do you have some other tool you would rather see me try?
See lib/path.c and lib/sysfs.c in util-linux (https://github.com/karelzak/util-linux).
For example ul_path_read() and ul_path_scanf().
We use it for lsblk, lsmem, lscpu, etc.
$ git grep -c ul_path_read misc-utils/lsblk.c sys-utils/lscpu.c
misc-utils/lsblk.c:30
sys-utils/lscpu.c:31
We're probably a little bit off-topic here, no problem to continue on
util-linux@...r.kernel.org or by private mails. Thanks!
Karel
--
Karel Zak <kzak@...hat.com>
http://karelzak.blogspot.com
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