From: Jiri Kosina <jkosina@suse.cz>
To: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
Cc: Jiri Slaby <jslaby@suse.cz>,
linux-kernel@vger.kernel.org, tj@kernel.org, rostedt@goodmis.org,
mingo@redhat.com, akpm@linux-foundation.org, andi@firstfloor.org,
paulmck@linux.vnet.ibm.com, pavel@ucw.cz, jirislaby@gmail.com,
Vojtech Pavlik <vojtech@suse.cz>, Michael Matz <matz@suse.de>
Subject: Re: [PATCH 00/21] kGraft
Date: Wed, 25 Jun 2014 17:54:50 +0200 (CEST) [thread overview]
Message-ID: <alpine.LNX.2.00.1406251748170.15939@pobox.suse.cz> (raw)
In-Reply-To: <20140625135421.67cd5f5f@alan.etchedpixels.co.uk>
On Wed, 25 Jun 2014, One Thousand Gnomes wrote:
> > this is a repost of the second round of RFC on kGraft, the linux
> > kernel online patching developed at SUSE. This repost only widened the
> > target audience for broader review, no code change happened.
>
> - wait_event_freezable(khubd_wait,
> + wait_event_freezable(khubd_wait,
> ({ kgr_task_safe(current);
>
> The changes are somewhat ugly with all the kgraft crap leaking into plces
> like jbd and freezer and usb. That says to me its not well isolated and
> there must be a better way of hiding that kgr stuff so we don't have to
> kepe putting more code into all the kthreads, and inevitably missing them
> or have people getting it wrong.
Tejun commented on this very issue during the first RFC submission a
couple weeks ago. Part of his proposal was actually to take this as a good
pretext to review the existing kernel threads, as the idea is that a big
portion of those could easily be converted to workqueues.
It of course has its own implications, such as not being able to
prioritize that easily, but there is probably a lot of low-hanging fruits
where driver authors and their grandmas have been creating kthreads where
workqueue would suffice.
But it's a very long term goal, and it's probably impractical to make
kGraft dependent on it.
> You add instructions to various hotpaths (despite the CONFIG comment).
Kernel entry is hidden behind _TIF_WORK_SYSCALL_ENTRY and
_TIF_ALLWORK_MASK, so it doesn't add any overhead if kGraft is not
enabled. What other hot paths do you refer to?
> Don't get me wrong - I'd like a good working ksplice/graft !
Thanks Alan,
--
Jiri Kosina
SUSE Labs
next prev parent reply other threads:[~2014-06-25 15:54 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-25 11:05 [PATCH 00/21] kGraft Jiri Slaby
2014-06-25 12:54 ` One Thousand Gnomes
2014-06-25 15:54 ` Jiri Kosina [this message]
2014-06-26 5:50 ` Vojtech Pavlik
2014-07-02 12:04 ` kGraft to -next [was: 00/21 kGraft] Jiri Slaby
2014-07-02 12:30 ` Tejun Heo
2014-07-02 12:47 ` One Thousand Gnomes
2014-07-02 13:01 ` Jiri Kosina
2014-07-02 13:30 ` Tejun Heo
2014-07-05 20:04 ` Jiri Kosina
2014-07-05 20:36 ` Tejun Heo
2014-07-05 20:49 ` Jiri Kosina
2014-07-05 21:04 ` Tejun Heo
2014-07-05 21:06 ` Jiri Kosina
2014-07-05 21:08 ` Tejun Heo
2014-07-29 14:05 ` Jiri Kosina
2014-07-02 12:47 ` Steven Rostedt
2014-07-02 16:28 ` Josh Poimboeuf
2014-07-03 0:26 ` Stephen Rothwell
-- strict thread matches above, loose matches on Subject: below --
2014-06-23 13:29 [PATCH 01/21] ftrace: Add function to find fentry of function Jiri Slaby
2014-06-23 13:51 ` [PATCH 00/21] kGraft Jiri Slaby
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