From: Roland Dreier <rdreier-FYB4Gu1CFyUAvxtiuMwx3w@public.gmane.org>
To: Jason Gunthorpe
<jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
Cc: Brice Goglin <Brice.Goglin-MZpvjPyXg2s@public.gmane.org>,
KOSAKI Motohiro
<kosaki.motohiro-+CUm20s59erQFUHtdCDX3A@public.gmane.org>,
linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
general-ZwoEplunGu1OwGhvXhtEPSCwEArCW2h5@public.gmane.org,
akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org,
torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org
Subject: Re: [ofa-general] Re: [GIT PULL] please pull ummunotify
Date: Fri, 11 Sep 2009 09:58:10 -0700 [thread overview]
Message-ID: <adaljklifkt.fsf@cisco.com> (raw)
In-Reply-To: <20090911064019.GZ4973-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org> (Jason Gunthorpe's message of "Fri, 11 Sep 2009 00:40:19 -0600")
> So.. What is the problem with fork? The semantics of what should
> happen seem natural enough to me, the PD doesn't get copied to the
> child, so the MR stays with the parent. COW events on the pinned
> region must be resolved so that the physical page stays with the
> process that has pinned it - the pin is logically released in the
> child because the MR doesn't exist because the PD doesn't exist.
This is getting away from the problem that ummunotify is solving, but
handling a COW fault generated by the parent by doing the copy in the
child seems like a pretty major, tricky change to make. The child may
have forked 100 more times in the meantime, meaning we now have to
change 101 memory maps ... the cost of page faults goes through the roof
probably...
- R.
--
To unsubscribe from this list: send the line "unsubscribe linux-rdma" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
WARNING: multiple messages have this Message-ID (diff)
From: Roland Dreier <rdreier@cisco.com>
To: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Cc: Brice Goglin <Brice.Goglin@inria.fr>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org,
general@lists.openfabrics.org, akpm@linux-foundation.org,
torvalds@linux-foundation.org
Subject: Re: [ofa-general] Re: [GIT PULL] please pull ummunotify
Date: Fri, 11 Sep 2009 09:58:10 -0700 [thread overview]
Message-ID: <adaljklifkt.fsf@cisco.com> (raw)
In-Reply-To: <20090911064019.GZ4973@obsidianresearch.com> (Jason Gunthorpe's message of "Fri, 11 Sep 2009 00:40:19 -0600")
> So.. What is the problem with fork? The semantics of what should
> happen seem natural enough to me, the PD doesn't get copied to the
> child, so the MR stays with the parent. COW events on the pinned
> region must be resolved so that the physical page stays with the
> process that has pinned it - the pin is logically released in the
> child because the MR doesn't exist because the PD doesn't exist.
This is getting away from the problem that ummunotify is solving, but
handling a COW fault generated by the parent by doing the copy in the
child seems like a pretty major, tricky change to make. The child may
have forked 100 more times in the meantime, meaning we now have to
change 101 memory maps ... the cost of page faults goes through the roof
probably...
- R.
next prev parent reply other threads:[~2009-09-11 16:58 UTC|newest]
Thread overview: 82+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-09-11 4:38 [GIT PULL] please pull ummunotify Roland Dreier
2009-09-11 4:38 ` Roland Dreier
2009-09-15 11:34 ` Pavel Machek
[not found] ` <20090915113434.GF1328-+ZI9xUNit7I@public.gmane.org>
2009-09-15 14:57 ` [ofa-general] " Roland Dreier
2009-09-15 14:57 ` Roland Dreier
[not found] ` <ada7hw0gsqz.fsf-FYB4Gu1CFyUAvxtiuMwx3w@public.gmane.org>
2009-09-28 20:49 ` Pavel Machek
2009-09-28 20:49 ` Pavel Machek
[not found] ` <20090928204923.GA1960-I/5MKhXcvmPrBKCeMvbIDA@public.gmane.org>
2009-09-28 21:40 ` Jason Gunthorpe
2009-09-28 21:40 ` Jason Gunthorpe
[not found] ` <aday6omhz9d.fsf-FYB4Gu1CFyUAvxtiuMwx3w@public.gmane.org>
2009-09-11 5:56 ` KOSAKI Motohiro
2009-09-11 5:56 ` KOSAKI Motohiro
2009-09-11 6:03 ` [ofa-general] " Roland Dreier
2009-09-11 6:03 ` Roland Dreier
[not found] ` <adatyzahvbm.fsf-FYB4Gu1CFyUAvxtiuMwx3w@public.gmane.org>
2009-09-11 6:11 ` KOSAKI Motohiro
2009-09-11 6:11 ` KOSAKI Motohiro
[not found] ` <20090911150552.DB68.A69D9226-+CUm20s59erQFUHtdCDX3A@public.gmane.org>
2009-09-11 16:42 ` Gleb Natapov
2009-09-11 16:42 ` Gleb Natapov
2009-09-11 6:15 ` Brice Goglin
[not found] ` <4AA9EAF7.5010401-MZpvjPyXg2s@public.gmane.org>
2009-09-11 6:21 ` KOSAKI Motohiro
2009-09-11 6:21 ` KOSAKI Motohiro
2009-09-11 6:22 ` Roland Dreier
2009-09-11 6:22 ` Roland Dreier
2009-09-11 6:40 ` [ofa-general] " Jason Gunthorpe
2009-09-11 6:40 ` Jason Gunthorpe
[not found] ` <20090911064019.GZ4973-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2009-09-11 16:58 ` Roland Dreier [this message]
2009-09-11 16:58 ` Roland Dreier
[not found] ` <adaljklifkt.fsf-FYB4Gu1CFyUAvxtiuMwx3w@public.gmane.org>
2009-09-15 7:03 ` KOSAKI Motohiro
2009-09-15 7:03 ` KOSAKI Motohiro
2009-09-15 8:27 ` Roland Dreier
2009-09-15 8:27 ` Roland Dreier
2009-09-15 12:38 ` Jeff Squyres
2009-09-15 12:38 ` Jeff Squyres
2009-09-16 16:30 ` Roland Dreier
2009-09-16 16:30 ` Roland Dreier
2009-09-16 16:40 ` [ofa-general] " Linus Torvalds
2009-09-16 16:40 ` Linus Torvalds
2009-09-17 11:30 ` Peter Zijlstra
2009-09-17 11:30 ` Peter Zijlstra
2009-09-17 14:24 ` [ofa-general] " Roland Dreier
[not found] ` <adafxalejiq.fsf-FYB4Gu1CFyUAvxtiuMwx3w@public.gmane.org>
2009-09-17 14:32 ` Roland Dreier
2009-09-17 14:32 ` Roland Dreier
[not found] ` <adaab0tej5c.fsf-FYB4Gu1CFyUAvxtiuMwx3w@public.gmane.org>
2009-09-17 14:49 ` Peter Zijlstra
2009-09-17 14:49 ` Peter Zijlstra
2009-09-17 15:03 ` Roland Dreier
2009-09-17 15:03 ` Roland Dreier
[not found] ` <adazl8td35u.fsf-FYB4Gu1CFyUAvxtiuMwx3w@public.gmane.org>
2009-09-17 15:22 ` Peter Zijlstra
2009-09-17 15:22 ` Peter Zijlstra
2009-09-17 15:45 ` Roland Dreier
2009-09-17 15:45 ` Roland Dreier
[not found] ` <adatyz1d17q.fsf-FYB4Gu1CFyUAvxtiuMwx3w@public.gmane.org>
2009-09-18 11:50 ` Ingo Molnar
2009-09-18 11:50 ` Ingo Molnar
2009-09-29 17:13 ` Pavel Machek
2009-09-29 17:13 ` Pavel Machek
[not found] ` <20090929171332.GD14405-I/5MKhXcvmPrBKCeMvbIDA@public.gmane.org>
2009-09-30 9:44 ` Ingo Molnar
2009-09-30 9:44 ` Ingo Molnar
[not found] ` <20090930094456.GD24621-X9Un+BFzKDI@public.gmane.org>
2009-09-30 16:02 ` Jason Gunthorpe
2009-09-30 16:02 ` Jason Gunthorpe
[not found] ` <20090930160232.GZ22310-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2009-10-12 18:19 ` Ingo Molnar
2009-10-12 18:19 ` Ingo Molnar
[not found] ` <20091012181944.GF17138-X9Un+BFzKDI@public.gmane.org>
2009-10-12 19:30 ` Jason Gunthorpe
2009-10-12 19:30 ` Jason Gunthorpe
2009-10-12 20:20 ` Ingo Molnar
[not found] ` <20091012202046.GA7648-X9Un+BFzKDI@public.gmane.org>
2009-10-13 4:05 ` Jason Gunthorpe
2009-10-13 4:05 ` Jason Gunthorpe
2009-10-13 6:40 ` Ingo Molnar
[not found] ` <20091013064006.GC9470-X9Un+BFzKDI@public.gmane.org>
2009-10-13 16:27 ` Jason Gunthorpe
2009-10-13 16:27 ` Jason Gunthorpe
2009-10-13 5:43 ` Brice Goglin
[not found] ` <4AD41373.8010108-MZpvjPyXg2s@public.gmane.org>
2009-10-13 6:38 ` Ingo Molnar
2009-10-13 6:38 ` Ingo Molnar
2009-09-30 17:06 ` Roland Dreier
2009-09-30 17:06 ` Roland Dreier
2009-10-02 16:32 ` Roland Dreier
2009-10-02 16:32 ` Roland Dreier
[not found] ` <ada3a61rc3j.fsf-FYB4Gu1CFyUAvxtiuMwx3w@public.gmane.org>
2009-10-02 20:45 ` Pavel Machek
2009-10-02 20:45 ` Pavel Machek
2009-10-07 22:34 ` Roland Dreier
2009-10-07 22:34 ` Roland Dreier
[not found] ` <ada3a5uq1dk.fsf-FYB4Gu1CFyUAvxtiuMwx3w@public.gmane.org>
2009-10-12 17:33 ` Peter Zijlstra
2009-10-12 17:33 ` Peter Zijlstra
2009-09-17 14:43 ` Peter Zijlstra
2009-09-17 14:43 ` Peter Zijlstra
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=adaljklifkt.fsf@cisco.com \
--to=rdreier-fyb4gu1cfyuavxtiumwx3w@public.gmane.org \
--cc=Brice.Goglin-MZpvjPyXg2s@public.gmane.org \
--cc=akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org \
--cc=general-ZwoEplunGu1OwGhvXhtEPSCwEArCW2h5@public.gmane.org \
--cc=jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org \
--cc=kosaki.motohiro-+CUm20s59erQFUHtdCDX3A@public.gmane.org \
--cc=linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
--cc=linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
--cc=torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org \
/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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.