linux-kernel - Re: [PATCH] hrtimer: make epoll_wait() use the hrtimer range feature

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Message-ID: <alpine.DEB.2.00.1008261612230.25446@makko.or.mcafeemobile.com>
Date:	Thu, 26 Aug 2010 16:23:00 -0700 (PDT)
From:	Davide Libenzi <davidel@...ilserver.org>
To:	Thomas Gleixner <tglx@...utronix.de>
cc:	Shawn Bohrer <shawn.bohrer@...il.com>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	linux-fsdevel@...r.kernel.org,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Arjan van de Ven <arjan@...radead.org>
Subject: Re: [PATCH] hrtimer: make epoll_wait() use the hrtimer range
 feature

On Fri, 27 Aug 2010, Thomas Gleixner wrote:

> On Thu, 26 Aug 2010, Davide Libenzi wrote:
> > On Sun, 8 Aug 2010, Shawn Bohrer wrote:
> > 
> > > This make epoll use hrtimers for the timeout value which prevents
> > > epoll_wait() from timing out up to a millisecond early.
> > > 
> > > This mirrors the behavior of select() and poll().
> > 
> > I saw this now, since I got notifications from Andrew's patch machine.
> > Is this really needed?
> 
> Yes, as it is the last user space interface which is jiffies based.

What? You killed jiffies?! :)
Alright then, the patch itself, besides the different bahavior on timeout 
greater/equal to EP_MAX_MSTIMEO (which is not documented, hence does not 
exist), looks OK to me.



- Davide


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