linux-kernel - Re: [PATCHv2 11/11] writeback: prevent unnecessary bdi threads wakeups

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Message-ID: <20100722085932.GA1254@amd>
Date:	Thu, 22 Jul 2010 18:59:32 +1000
From:	Nick Piggin <npiggin@...e.de>
To:	Artem Bityutskiy <dedekind1@...il.com>
Cc:	Nick Piggin <npiggin@...e.de>,
	Kristo Tero Tapani <tero.kristo@...ia.com>,
	Jens Axboe <axboe@...nel.dk>, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCHv2 11/11] writeback: prevent unnecessary bdi threads
 wakeups

On Thu, Jul 22, 2010 at 11:02:19AM +0300, Artem Bityutskiy wrote:
> On Thu, 2010-07-22 at 18:05 +1000, Nick Piggin wrote:
> > I can see what you mean, but I think the designs in core code should
> > be made as efficient as possible _unless_ there is some complication
> > in doing otherwise (not the other way around).
> > 
> > This is producing 2 unrequired context switches, so I really would
> > like to see it done properly. Setting up a timer is really pretty
> > simple (or if you would care to implement a delayed process wakeup
> > API, I think that would be useful -- I'm surprised there isn't one
> > already).
> 
> OK, NP, I'll work on this.

Thanks.

 
> The only problem I see is that it will involve more maintainers and
> trees (I guess Ingo?), and make it even more difficult for me to reach
> upstream :-) But let's try and see!

I wouldn't worry about that. It's so simple that if you end up coding
the helper function to do a timer delayed wakeup, just send it to Jens
in your series, cc Ingo on it if you'd like.

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