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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: mtk.manpages@gmail.com, shuah@kernel.org,
	linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-man@vger.kernel.org,
	linux-kselftest@vger.kernel.org
Subject: Re: [PATCH 0/3] readfile(2): a new syscall to make open/read/close faster
Date: Sun, 5 Jul 2020 13:47:06 +0200
Message-ID: <20200705114706.GA1227487@kroah.com> (raw)
In-Reply-To: <20200704193040.GC2786714@ZenIV.linux.org.uk>

On Sat, Jul 04, 2020 at 08:30:40PM +0100, Al Viro wrote:
> On Sat, Jul 04, 2020 at 04:02:46PM +0200, Greg Kroah-Hartman wrote:
> > Here is a tiny new syscall, readfile, that makes it simpler to read
> > small/medium sized files all in one shot, no need to do open/read/close.
> > This is especially helpful for tools that poke around in procfs or
> > sysfs, making a little bit of a less system load than before, especially
> > as syscall overheads go up over time due to various CPU bugs being
> > addressed.
> 
> Nice series, but you are 3 months late with it...  Next AFD, perhaps?

Perhaps :)

> Seriously, the rationale is bollocks.  If the overhead of 2 extra
> syscalls is anywhere near the costs of the real work being done by
> that thing, we have already lost and the best thing to do is to
> throw the system away and start with saner hardware.

The real-work the kernel does is almost neglegant compared to the
open/close overhead of the syscalls on some platforms today.  I'll post
benchmarks with the next version of this patch series to hopefully show
that.  If not, then yeah, this isn't worth it, but it was fun to write.

thanks,

greg k-h

  reply index

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-04 14:02 Greg Kroah-Hartman
2020-07-04 14:02 ` [PATCH 1/3] readfile: implement readfile syscall Greg Kroah-Hartman
2020-07-04 18:35   ` Geert Uytterhoeven
2020-07-04 19:14   ` Matthew Wilcox
2020-07-04 19:41   ` Miklos Szeredi
2020-07-04 20:12     ` Al Viro
2020-07-04 20:16       ` Al Viro
2020-07-04 14:02 ` [PATCH 2/3] arch: wire up the " Greg Kroah-Hartman
2020-07-04 18:36   ` Geert Uytterhoeven
2020-07-04 14:02 ` [PATCH 3/3] selftests: add readfile(2) selftests Greg Kroah-Hartman
2020-07-04 18:38   ` Geert Uytterhoeven
2020-07-05  6:55     ` Greg Kroah-Hartman
2020-07-05 11:24       ` Geert Uytterhoeven
2020-07-05 11:36         ` Greg Kroah-Hartman
2020-07-05  1:41   ` Heinrich Schuchardt
2020-07-05  7:34     ` Greg Kroah-Hartman
2020-07-05  9:46       ` Heinrich Schuchardt
2020-07-04 14:02 ` [PATCH] readfile.2: new page describing readfile(2) Greg Kroah-Hartman
2020-07-05  2:54   ` Heinrich Schuchardt
2020-07-04 19:30 ` [PATCH 0/3] readfile(2): a new syscall to make open/read/close faster Al Viro
2020-07-05 11:47   ` Greg Kroah-Hartman [this message]
2020-07-06 17:25 ` Dave Martin
2020-07-05  2:06 Jan Ziak
2020-07-05  2:16 ` Matthew Wilcox
2020-07-05  2:46   ` Jan Ziak
2020-07-05  3:12     ` Matthew Wilcox
2020-07-05  3:18       ` Jan Ziak
2020-07-05  3:27         ` Matthew Wilcox
2020-07-05  4:09           ` Jan Ziak
2020-07-05 11:58             ` Greg KH
2020-07-06  6:07               ` Jan Ziak
2020-07-06 11:11                 ` Matthew Wilcox
2020-07-06 11:18                 ` Greg KH
2020-07-05  8:07           ` Vito Caputo
2020-07-05 11:44             ` Greg KH
2020-07-05 20:34               ` Vito Caputo
2020-07-05  6:32     ` Andreas Dilger
2020-07-05  7:25       ` Jan Ziak
2020-07-05 12:00         ` Greg KH
2020-07-05 11:50 ` Greg KH
2020-07-14  6:51   ` Pavel Machek
2020-07-14  8:07     ` Miklos Szeredi
2020-07-14 11:34       ` Pavel Begunkov
2020-07-14 11:55         ` Miklos Szeredi
2020-07-15  8:31           ` Pavel Begunkov
2020-07-15  8:41             ` Miklos Szeredi
2020-07-15  8:49               ` Pavel Begunkov
2020-07-15  9:00                 ` Pavel Begunkov
2020-07-15 11:17                   ` Miklos Szeredi

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