linux-kernel - Re: [RFC][PATCH] create workqueue threads only when needed

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Sat, 31 Jan 2009 19:28:45 +0100
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Arjan van de Ven <arjan@...radead.org>
Cc:	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Lai Jiangshan <laijs@...fujitsu.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [RFC][PATCH] create workqueue threads only when needed

On Sat, Jan 31, 2009 at 10:15:02AM -0800, Arjan van de Ven wrote:
> On Sat, 31 Jan 2009 19:03:49 +0100
> Frederic Weisbecker <fweisbec@...il.com> wrote:
> 
> > > one thing to look at for work queues that never get work is to see
> > > if they are appropriate for the async function call interface
> > > (the only requirement for that is that they need to cope with
> > > calling inline in exceptional cases)
> > > 
> > 
> > 
> > Hi Arjan,
> > 
> > There is one thing that make it hard to replace workqueues in such
> > cases, there is not guarantee the function will run in user context
> > because of this condition:
> > 
> > if (!async_enabled || !entry || atomic_read(&entry_count) > MAX_WORK)
> > 
> > I wanted to replace kpsmoused with an async function but I want to
> > schedule a slow work that can't be done from irq...
> 
> if there is enough value in having a variant that is guaranteed to
> always run from a thread we could add that. Likely that needs that the 
> caller passes in a bit of memory, but that's not too big a deal.
> If there is only 1 in the entire kernel it might not be worth it,
> but if it's a common pattern then for sure...
> 
> do you have a feeling on how common this is ?
> 


I don't know, most of those I've looked on are not documented about the reason
for a private workqueue. I guess most of them can use the usual kevent.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/