linux-kernel - Re: [RFC PATCH] fs/exec: Add the support for ELF program's NUMA replication

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Message-ID: <YTYE8tBNAhK0MXsY@casper.infradead.org>
Date:   Mon, 6 Sep 2021 13:09:22 +0100
From:   Matthew Wilcox <willy@...radead.org>
To:     Huang Shijie <shijie@...amperecomputing.com>
Cc:     viro@...iv.linux.org.uk, akpm@...ux-foundation.org,
        jlayton@...nel.org, bfields@...ldses.org,
        torvalds@...ux-foundation.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        song.bao.hua@...ilicon.com, patches@...erecomputing.com,
        zwang@...erecomputing.com
Subject: Re: [RFC PATCH] fs/exec: Add the support for ELF program's NUMA
 replication

On Mon, Sep 06, 2021 at 04:16:13PM +0000, Huang Shijie wrote:
> This patch adds AT_NUMA_REPLICATION for execveat().
> 
> If this flag is set, the kernel will trigger COW(copy on write)
> on the mmapped ELF binary. So the program will have a copied-page
> on its NUMA node, even if the original page in page cache is
> on other NUMA nodes.

This does absolutely nothing for programs which run on multiple NUMA
nodes at the same time.

Also, I dislike the abuse of the term "COW" for this.  It's COF --
Copy On Fault.