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From: Gao Xiang <hsiangkao@aol.com>
To: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Gao Xiang" <gaoxiang25@huawei.com>,
	devel@driverdev.osuosl.org,
	"Christoph Hellwig" <hch@infradead.org>,
	"Valdis Klētnieks" <valdis.kletnieks@vt.edu>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	linux-kernel@vger.kernel.org,
	"Sasha Levin" <alexander.levin@microsoft.com>,
	linux-fsdevel@vger.kernel.org,
	"OGAWA Hirofumi" <hirofumi@mail.parknet.co.jp>
Subject: Re: [PATCH] staging: exfat: add exfat filesystem code to staging
Date: Fri, 30 Aug 2019 20:04:20 +0800
Message-ID: <20190830120419.GB10981@hsiangkao-HP-ZHAN-66-Pro-G1> (raw)
In-Reply-To: <20190830112612.GF8372@kadam>

Hi Dan,

On Fri, Aug 30, 2019 at 02:26:12PM +0300, Dan Carpenter wrote:
> On Fri, Aug 30, 2019 at 04:43:33PM +0800, Gao Xiang wrote:
> > Hi Dan,
> > 
> > On Fri, Aug 30, 2019 at 11:34:45AM +0300, Dan Carpenter wrote:
> > > On Fri, Aug 30, 2019 at 12:04:41AM +0800, Gao Xiang wrote:
> > > > Anyway, I'm fine to delete them all if you like, but I think majority of these
> > > > are meaningful.
> > > > 
> > > > data.c-		/* page is already locked */
> > > > data.c-		DBG_BUGON(PageUptodate(page));
> > > > data.c-
> > > > data.c:		if (unlikely(err))
> > > > data.c-			SetPageError(page);
> > > > data.c-		else
> > > > data.c-			SetPageUptodate(page);
> > > 
> > > If we cared about speed here then we would delete the DBG_BUGON() check
> > > because that's going to be expensive.  The likely/unlikely annotations
> > > should be used in places a reasonable person thinks it will make a
> > > difference to benchmarks.
> > 
> > DBG_BUGON will be a no-op ((void)x) in non-debugging mode,
> 
> It expands to:
> 
> 	((void)PageUptodate(page));
> 
> Calling PageUptodate() doesn't do anything, but it isn't free.  The
> time it takes to do that function call completely negates any speed up
> from using likely/unlikely.
> 
> I'm really not trying to be a jerk...

You are right, I recalled that PageUptodate is not as simple as it implys.
Yes, those are all removed now... I am ok with that,
thanks for your suggestion :)

Thanks,
Gao Xiang

> 
> regards,
> dan carpenter
>
 

  reply index

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-28 16:08 Greg Kroah-Hartman
2019-08-28 17:00 ` Greg Kroah-Hartman
2019-08-29  6:23   ` Christoph Hellwig
2019-08-29  6:39     ` Greg Kroah-Hartman
2019-08-29  9:41       ` Christoph Hellwig
2019-08-29  9:50         ` Greg Kroah-Hartman
2019-08-29 10:37           ` Christoph Hellwig
2019-08-29 11:04             ` Gao Xiang
2019-08-29 11:18               ` Greg Kroah-Hartman
2019-08-29 11:18             ` Greg Kroah-Hartman
2019-08-29 15:11               ` Dan Carpenter
2019-08-29 15:27                 ` Gao Xiang
2019-08-29 15:43                   ` Dan Carpenter
2019-08-29 15:51                     ` Gao Xiang
2019-08-29 16:04                       ` Gao Xiang
2019-08-30  8:34                         ` Dan Carpenter
2019-08-30  8:43                           ` Gao Xiang
2019-08-30 11:26                             ` Dan Carpenter
2019-08-30 12:04                               ` Gao Xiang [this message]
2019-08-29 16:44                     ` Gao Xiang
2019-08-29 16:59                       ` Joe Perches
2019-08-29 17:02                         ` Gao Xiang
2019-08-30  2:06                     ` Chao Yu
2019-08-30  6:38                       ` Gao Xiang
2019-08-30 12:00                         ` Checking usage of likeliness annotations Markus Elfring
2019-08-30 11:51                       ` [PATCH] staging: exfat: add exfat filesystem code to staging David Sterba
2019-08-31  3:50                         ` Chao Yu
2019-08-30 15:36               ` Christoph Hellwig
2019-08-30 21:54               ` Dave Chinner
2019-08-31 10:31                 ` Valdis Klētnieks
2019-09-01  0:04                   ` Dave Chinner
2019-08-29  7:01     ` Gao Xiang
2019-08-29  8:24       ` Gao Xiang
2019-08-29  9:51         ` Christoph Hellwig
2019-08-29 12:14 ` Pali Rohár
2019-08-29 12:34   ` Valdis Klētnieks
2019-08-29 12:46     ` Pali Rohár
2019-08-29 14:08 ` Markus Elfring
2019-08-29 15:44 ` Markus Elfring
2019-08-29 20:56 ` Pali Rohár
2019-08-29 23:18   ` Valdis Klētnieks
2019-08-29 23:35     ` Sasha Levin
2019-08-30  7:56       ` Pali Rohár
2019-08-30  8:03     ` Pali Rohár
2019-08-30 15:40   ` Christoph Hellwig
2019-08-30 15:43     ` Pali Rohár
2019-09-14 13:39 ` [PATCH] staging: exfat: add exfat filesystem code to Park Ju Hyung
2019-09-15 13:54   ` Greg KH
2019-09-15 16:11     ` Ju Hyung Park
     [not found] ` <20190918195920.25210-1-qkrwngud825@gmail.com>
2019-09-18 20:12   ` [PATCH] staging: exfat: rebase to sdFAT v2.2.0 Greg KH
2019-09-18 20:13   ` Greg KH
2019-09-18 20:22     ` Ju Hyung Park
2019-09-18 20:26       ` Greg KH
2019-09-18 20:31         ` Ju Hyung Park
2019-09-18 20:46           ` Valdis Klētnieks
2019-09-18 21:31   ` kbuild test robot
2019-09-18 21:31   ` kbuild test robot
2019-09-18 22:17     ` Ju Hyung Park

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