From: Onkalo Samu <samu.p.onkalo@nokia.com>
To: ext Alan Cox <alan@linux.intel.com>
Cc: Ming Lei <tom.leiming@gmail.com>,
"gregkh@suse.de" <gregkh@suse.de>,
"hmh@hmh.eng.br" <hmh@hmh.eng.br>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH] device-core: sysfs open - close notify
Date: Tue, 02 Nov 2010 08:30:08 +0200 [thread overview]
Message-ID: <1288679408.2080.18.camel@noppispoppis.nmp.nokia.com> (raw)
In-Reply-To: <20101101171126.1194e2b0@linux.intel.com>
On Mon, 2010-11-01 at 18:11 +0100, ext Alan Cox wrote:
> > Your patch may cause many unnecessary memory waste because
> > most of drivers does not need attribute file .open/.close notifier.
>
> Firstly there are not that many driver objects in a small system so it
> wouldn't take that much to shift the balance the other way. Secondly
> its becoming clear that every time a driver goes to runtime pm these
> issues come up - even with things like configuration values for drivers
> that need to wake the hardware and then silence it.
>
> So the whole sysfs/open thing is going to keep haunting us with runtime
> pm, the question is where to put the callbacks so we don't bloat stuff.
> Clearly not per attribute or per sysfs node. One possibility would be
> with the runtime pm stuff, but that would need a clean reliable way to
> go sysfs->device->runtime_pm
>
> There are also obvious hackish ways to handle it like passing a 0
> length read to indicate close etc - they save memory but they are
> asking for problems in future.
>
Memory footprint could be minimized by combining separate open close
functions to one like sysfs_open_close_notify and the actual operation
would be a call parameter. But is that hackish?
And perhaps some flags could be used to indicate which attributes trigs
the open / close notification.
-Samu
next prev parent reply other threads:[~2010-11-02 6:31 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-31 12:46 [RFC PATCH] device-core: sysfs open - close notify Samu Onkalo
2010-10-31 16:14 ` Ming Lei
2010-11-01 17:11 ` Alan Cox
2010-11-02 6:30 ` Onkalo Samu [this message]
2010-11-16 3:14 ` Enrico Weigelt
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