linux-kernel - Re: [PATCH 2/2] mm, rmap: handle anon_vma

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Message-ID: <b35ed617-0508-91f1-972b-801932320264@huawei.com>
Date: Tue, 10 Dec 2024 10:25:35 +0800
From: Jinjie Ruan <ruanjinjie@...wei.com>
To: Matthew Wilcox <willy@...radead.org>
CC: <viro@...iv.linux.org.uk>, <brauner@...nel.org>, <jack@...e.cz>,
	<akpm@...ux-foundation.org>, <Liam.Howlett@...cle.com>,
	<lokeshgidra@...gle.com>, <lorenzo.stoakes@...cle.com>, <rppt@...nel.org>,
	<aarcange@...hat.com>, <Jason@...c4.com>, <linux-fsdevel@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>
Subject: Re: [PATCH 2/2] mm, rmap: handle anon_vma_fork() NULL check inline



On 2024/12/9 21:35, Matthew Wilcox wrote:
> On Mon, Dec 09, 2024 at 09:25:49PM +0800, Jinjie Ruan wrote:
>> Check the anon_vma of pvma inline so we can avoid the function call
>> overhead if the anon_vma is NULL.
> 
> This really gets you 1% perf improvement?  On what hardware?

Yes，the total improvement of this two patches is about 1% on our
last-generation arm64 server platform.

During the test of Unixbench single-core process creation, the trace
result shows that the two functions are frequently invoked, and a large
number of check NULL and returned.

> 
>