Linux-parisc archive on lore.kernel.org
 help / color / Atom feed
From: David Laight <David.Laight@ACULAB.COM>
To: 'Eric Dumazet' <edumazet@google.com>,
	Nate Karstens <nate.karstens@garmin.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
	Jeff Layton <jlayton@kernel.org>,
	"J. Bruce Fields" <bfields@fieldses.org>,
	Arnd Bergmann <arnd@arndb.de>,
	Richard Henderson <rth@twiddle.net>,
	Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
	Matt Turner <mattst88@gmail.com>,
	"James E.J. Bottomley" <James.Bottomley@hansenpartnership.com>,
	Helge Deller <deller@gmx.de>,
	"David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	linux-arch <linux-arch@vger.kernel.org>,
	"linux-alpha@vger.kernel.org" <linux-alpha@vger.kernel.org>,
	"linux-parisc@vger.kernel.org" <linux-parisc@vger.kernel.org>,
	"sparclinux@vger.kernel.org" <sparclinux@vger.kernel.org>,
	netdev <netdev@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Changli Gao <xiaosuo@gmail.com>
Subject: RE: [PATCH v2] Implement close-on-fork
Date: Fri, 15 May 2020 15:59:58 +0000
Message-ID: <480b831115724107ab5a0cab9d7caafc@AcuMS.aculab.com> (raw)
In-Reply-To: <CANn89iKr_9MyRpdB4pcHm08ccH_M42etDnrOzpVKUYfhSKvxQw@mail.gmail.com>

From: Eric Dumazet
> Sent: 15 May 2020 16:31
...
> Fast path in big and performance sensitive applications is not fork()
> and/or exec().
> 
> This is open()/close() and others (socket(), accept(), ...)
> 
> We do not want them to access extra cache lines for this new feature.
> 
> Sorry, I will say no to these patches in their current form.

Is it worth completely removing the bitmaps and just remembering
the lowest fd that has had each bit set (don't worry about clears).

Then leverage the close_all() code that closes all fd above
a specified number to close only those with the 'close on exec'
or 'close on fork' flag set.

After all an application is currently very likely to have set
'close on exec' on all open fd above 2.

So the number of fd that don't need closing is small.

This puts all the expensive code in the already slow fork/exec
paths.

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)

  reply index

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-15 15:23 Nate Karstens
2020-05-15 15:23 ` [PATCH v2 1/4] fs: " Nate Karstens
2020-05-15 15:23 ` [PATCH v2 2/4] fs: Add O_CLOFORK flag for open(2) and dup3(2) Nate Karstens
2020-05-15 15:23 ` [PATCH v2 3/4] fs: Add F_DUPFD_CLOFORK to fcntl(2) Nate Karstens
2020-05-15 15:23 ` [PATCH v2 4/4] net: Add SOCK_CLOFORK Nate Karstens
2020-05-15 15:30 ` [PATCH v2] Implement close-on-fork Eric Dumazet
2020-05-15 15:59   ` David Laight [this message]
2020-05-15 15:57 ` Matthew Wilcox
2020-05-15 16:07   ` Karstens, Nate
2020-05-15 16:25     ` James Bottomley
2020-05-15 18:28       ` Karstens, Nate
2020-05-15 18:43         ` Matthew Wilcox
2020-05-25  8:16         ` Pavel Machek
2020-05-15 16:26     ` Matthew Wilcox
2020-05-16 13:29   ` Christian Brauner
2020-05-15 16:03 ` Al Viro
2020-05-15 16:26   ` Karstens, Nate
2020-05-15 16:53   ` David Howells

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=480b831115724107ab5a0cab9d7caafc@AcuMS.aculab.com \
    --to=david.laight@aculab.com \
    --cc=James.Bottomley@hansenpartnership.com \
    --cc=arnd@arndb.de \
    --cc=bfields@fieldses.org \
    --cc=davem@davemloft.net \
    --cc=deller@gmx.de \
    --cc=edumazet@google.com \
    --cc=ink@jurassic.park.msu.ru \
    --cc=jlayton@kernel.org \
    --cc=kuba@kernel.org \
    --cc=linux-alpha@vger.kernel.org \
    --cc=linux-arch@vger.kernel.org \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-parisc@vger.kernel.org \
    --cc=mattst88@gmail.com \
    --cc=nate.karstens@garmin.com \
    --cc=netdev@vger.kernel.org \
    --cc=rth@twiddle.net \
    --cc=sparclinux@vger.kernel.org \
    --cc=viro@zeniv.linux.org.uk \
    --cc=xiaosuo@gmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-parisc archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-parisc/0 linux-parisc/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-parisc linux-parisc/ https://lore.kernel.org/linux-parisc \
		linux-parisc@vger.kernel.org
	public-inbox-index linux-parisc

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-parisc


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git