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From: Pavel Skripkin <paskripkin@gmail.com>
To: David Laight <David.Laight@ACULAB.COM>,
	Michael Straube <straube.linux@gmail.com>,
	"Fabio M. De Francesco" <fmdefrancesco@gmail.com>
Cc: Greg KH <gregkh@linuxfoundation.org>,
	Larry Finger <Larry.Finger@lwfinger.net>,
	Phillip Potter <phil@philpotter.co.uk>,
	"open list:STAGING SUBSYSTEM" <linux-staging@lists.linux.dev>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: staging: r8188eu: how to handle nested mutex under spinlock
Date: Mon, 4 Apr 2022 19:38:55 +0300	[thread overview]
Message-ID: <3c8b6454-6b52-fe62-8db1-c76bdbeb2df0@gmail.com> (raw)
In-Reply-To: <4ef1e90716e64fd78ebbc222bbb7e597@AcuMS.aculab.com>


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Hi David,

On 4/4/22 11:50, David Laight wrote:
>> 
>> > 		while (pwrpriv->bInSuspend &&
>> 
>> I've looked into what gcc11 produced from this function and looks like
>> my compiler is smart enough to not cache that value, but I am afraid not
>> all compilers are that smart.
> 
> The compiler can't cache the value because of the function call.
> 

Hm, I am a newbie in compilers, so can you, please, explain (or give a 
link to any resource where I can read about it) how function call here 
prevent caching.

IIUC compiler generates code that works well in scope of single-threaded 
application, so why can't compiler cache that value instead of accessing 
memory on each iteration... Isn't register access a way faster than even 
cache hit?


Thanks!

With regards,
Pavel Skripkin

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  reply	other threads:[~2022-04-04 16:38 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-02 20:47 staging: r8188eu: how to handle nested mutex under spinlock Michael Straube
2022-04-02 21:13 ` Pavel Skripkin
2022-04-02 21:32 ` Larry Finger
2022-04-03  8:44   ` Michael Straube
     [not found] ` <4389354.LvFx2qVVIh@leap>
     [not found]   ` <1813843.tdWV9SEqCh@leap>
2022-04-03 11:08     ` Michael Straube
     [not found]       ` <7365301.EvYhyI6sBW@leap>
2022-04-03 11:41         ` Michael Straube
2022-04-03 11:48           ` Pavel Skripkin
     [not found]             ` <1817830.CQOukoFCf9@leap>
2022-04-03 12:14               ` Michael Straube
2022-04-03 12:19             ` Pavel Skripkin
     [not found]               ` <4412825.cEBGB3zze1@leap>
2022-04-03 12:45                 ` Pavel Skripkin
     [not found]                   ` <2029549.KlZ2vcFHjT@leap>
2022-04-03 13:02                     ` Pavel Skripkin
2022-04-03 20:51                       ` Michael Straube
2022-04-03 21:15                         ` Pavel Skripkin
2022-04-04  8:50                           ` David Laight
2022-04-04 16:38                             ` Pavel Skripkin [this message]
2022-04-04 16:59                               ` David Laight
2022-04-04 17:12                                 ` Pavel Skripkin
     [not found]           ` <1858641.taCxCBeP46@leap>
     [not found]             ` <2366209.jE0xQCEvom@leap>
2022-04-03 12:18               ` Michael Straube
2022-04-04 13:33                 ` Dan Carpenter
2022-04-04 14:16                   ` Michael Straube
     [not found]         ` <3097543.5fSG56mABF@leap>
2022-04-03 11:44           ` Michael Straube

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