linux-kernel - Re: [PATCH] mm: Add new vma flag VM_LOCAL

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Message-ID: <99bd469f-5cec-c537-ba3e-738956070a8f@netapp.com>
Date:   Tue, 15 May 2018 17:36:44 +0300
From:   Boaz Harrosh <boazh@...app.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Boaz Harrosh <boazh@...app.com>
CC:     Matthew Wilcox <willy@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Jeff Moyer <jmoyer@...hat.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, <x86@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Rik van Riel <riel@...hat.com>, Jan Kara <jack@...e.cz>,
        Matthew Wilcox <mawilcox@...rosoft.com>,
        Amit Golander <Amit.Golander@...app.com>
Subject: Re: [PATCH] mm: Add new vma flag VM_LOCAL_CPU

On 15/05/18 17:17, Peter Zijlstra wrote:
<>
>>
>> So I would love some mm guy to explain where are those bits collected?
> 
> Depends on the architecture, some architectures only ever set bits,
> some, like x86, clear bits again. You want to look at switch_mm().
> 
> Basically x86 clears the bit again when we switch away from the mm and
> have/will invalidate TLBs for it in doing so.
> 

Ha, OK I am starting to get a picture.

>> Which brings me to another question. How can I find from
>> within a thread Say at the file_operations->mmap() call that the thread
>> is indeed core-pinned. What mm_cpumask should I inspect?
> 
> is_percpu_thread().

Right thank you a lot Peter. this helps.

Boaz
> .
>