linux-kernel - Re: [RFC 1/4] mm: refactor __vunmap() to avoid duplicated call to find_vm

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Message-ID: <20181214182452.GD10600@bombadil.infradead.org>
Date:   Fri, 14 Dec 2018 10:24:52 -0800
From:   Matthew Wilcox <willy@...radead.org>
To:     Roman Gushchin <guroan@...il.com>
Cc:     linux-mm@...ck.org, Alexey Dobriyan <adobriyan@...il.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...e.com>,
        Vlastimil Babka <vbabka@...e.cz>, linux-kernel@...r.kernel.org,
        kernel-team@...com, Roman Gushchin <guro@...com>
Subject: Re: [RFC 1/4] mm: refactor __vunmap() to avoid duplicated call to
 find_vm_area()

On Fri, Dec 14, 2018 at 10:07:17AM -0800, Roman Gushchin wrote:
> __vunmap() calls find_vm_area() twice without an obvious reason:
> first directly to get the area pointer, second indirectly by calling
> remove_vm_area(), which is again searching for the area.
> 
> To remove this redundancy, let's split remove_vm_area() into
> __remove_vm_area(struct vmap_area *), which performs the actual area
> removal, and remove_vm_area(const void *addr) wrapper, which can
> be used everywhere, where it has been used before.
> 
> On my test setup, I've got up to 12% speed up on vfree()'ing 1000000
> of 4-pages vmalloc blocks.
> 
> Signed-off-by: Roman Gushchin <guro@...com>
> Acked-by: Johannes Weiner <hannes@...xchg.org>

Reviewed-by: Matthew Wilcox <willy@...radead.org>