From: Alan Stern <stern@rowland.harvard.edu>
To: Aaron Lu <aaron.lu@intel.com>
Cc: Jens Axboe <axboe@kernel.dk>, "Rafael J. Wysocki" <rjw@sisk.pl>,
James Bottomley <James.Bottomley@hansenpartnership.com>,
<linux-pm@vger.kernel.org>, <linux-scsi@vger.kernel.org>,
<linux-kernel@vger.kernel.org>, Aaron Lu <aaron.lwe@gmail.com>,
Shane Huang <shane.huang@amd.com>
Subject: Re: [PATCH v8 4/4] sd: change to auto suspend mode
Date: Fri, 1 Feb 2013 10:11:43 -0500 (EST) [thread overview]
Message-ID: <Pine.LNX.4.44L0.1302011011090.1752-100000@iolanthe.rowland.org> (raw)
In-Reply-To: <20130201031944.GA6960@aaronlu.sh.intel.com>
On Fri, 1 Feb 2013, Aaron Lu wrote:
> On Thu, Jan 31, 2013 at 10:13:05AM -0500, Alan Stern wrote:
> > On Thu, 31 Jan 2013, Aaron Lu wrote:
> >
> > > > > +static int scsi_blk_runtime_suspend(struct device *dev)
> > > > > +{
> > > > > + struct scsi_device *sdev = to_scsi_device(dev);
> > > >
> > > > For this routine and the other new ones, it may be slightly more
> > > > efficient to pass both dev and sdev as arguments (this depends on how
> > > > smart the compiler's optimizer is). The caller already knows both of
> > > > them, after all.
> > >
> > > What about passing only scsi_device? When device is needed, I can use
> > > &sdev->sdev_gendev. Is this equally efficient?
> >
> > I don't know... The difference is very small in any case. The
> > routines will probably be inlined automatically.
>
> Indeed, I just checked the .s output of the three cases, they are all
> the same. So we just need to care about readability and less of code,
> passing only scsi_device seems to be the simplest, are you OK with this?
Yes, that's fine. Thanks for checking it out.
Alan Stern
prev parent reply other threads:[~2013-02-01 15:11 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-30 9:34 [PATCH v8 0/4] block layer runtime pm Aaron Lu
2013-01-30 9:34 ` [PATCH v8 1/4] block: add a flag to identify PM request Aaron Lu
2013-01-30 9:34 ` [PATCH v8 2/4] block: add runtime pm helpers Aaron Lu
2013-01-30 15:54 ` Alan Stern
2013-01-31 5:35 ` Aaron Lu
2013-01-31 15:09 ` Alan Stern
2013-01-30 9:34 ` [PATCH v8 3/4] block: implement runtime pm strategy Aaron Lu
2013-01-30 9:34 ` [PATCH v8 4/4] sd: change to auto suspend mode Aaron Lu
2013-01-30 15:38 ` Alan Stern
2013-01-31 5:43 ` Aaron Lu
2013-01-31 15:13 ` Alan Stern
2013-02-01 3:19 ` Aaron Lu
2013-02-01 15:11 ` Alan Stern [this message]
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