From: Randy Dunlap <rdunlap@infradead.org>
To: Feng Tang <feng.tang@intel.com>
Cc: Jonathan Corbet <corbet@lwn.net>,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
Arnaldo Carvalho de Melo <acme@redhat.com>,
Joe Mario <jmario@redhat.com>, Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Eric Dumazet <edumazet@google.com>,
Shakeel Butt <shakeelb@google.com>,
dave.hansen@intel.com, ying.huang@intel.com,
tim.c.chen@intel.com, andi.kleen@intel.com
Subject: Re: [PATCH RFC] Documentation: Add document for false sharing
Date: Thu, 23 Mar 2023 21:30:14 -0700 [thread overview]
Message-ID: <d0032404-e627-2d51-9c7b-42f5cdf29929@infradead.org> (raw)
In-Reply-To: <ZB0S/gfCLGP44HME@feng-clx>
Hi--
On 3/23/23 20:03, Feng Tang wrote:
> Hi Randy,
>
> Thank you for the thorough reviews!
>
> On Thu, Mar 23, 2023 at 09:49:02AM -0700, Randy Dunlap wrote:
>> Hi,
>>
>> Lots of good/interesting info here.
>>
>> On 3/23/23 01:26, Feng Tang wrote:
>>> From: "Tang, Feng" <feng.tang@intel.com>
>>> +
>>> +'refcount' is modified frequently, but 'name' is set once at object
>>> +creation time and is never modified. When many CPUs access 'foo' at
>>> +the same time, and 'refcount' is only bumped by one CPU frequently,
>>> +while 'name' is read by all other CPUs, which have to reload the whole
>>> +cache line over and over, even though the 'name' is never changed.
>>
>> That last "sentence" is not a sentence.
>
> How about:
>
> "
> When many CPUs access 'foo' at the same time, with 'refcount' being only
> bumped by one CPU frequently and 'name' being read by other CPUs, all
> those reading CPUs have to reload the whole cache line over and over
> due to the 'sharing', even though 'name' is never changed.
> "
> ?
Yes, that's good. Thanks.
--
~Randy
prev parent reply other threads:[~2023-03-24 4:30 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-23 8:26 Feng Tang
2023-03-23 16:49 ` Randy Dunlap
2023-03-24 3:03 ` Feng Tang
2023-03-24 4:30 ` Randy Dunlap [this message]
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