linux-kernel - Re: [PATCH v2 3/4] mm/vmalloc: Use kvmalloc to allocate the table of pages

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Message-ID: <9e3d5e8a-4e47-d29a-8474-925036d8e5b@google.com>
Date:   Wed, 24 Mar 2021 12:04:45 -0700 (PDT)
From:   David Rientjes <rientjes@...gle.com>
To:     "Matthew Wilcox (Oracle)" <willy@...radead.org>
cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Christoph Lameter <cl@...ux.com>,
        Pekka Enberg <penberg@...nel.org>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Uladzislau Rezki <urezki@...il.com>,
        Nicholas Piggin <npiggin@...il.com>
Subject: Re: [PATCH v2 3/4] mm/vmalloc: Use kvmalloc to allocate the table
 of pages

On Wed, 24 Mar 2021, Matthew Wilcox (Oracle) wrote:

> If we're trying to allocate 4MB of memory, the table will be 8KiB in size
> (1024 pointers * 8 bytes per pointer), which can usually be satisfied
> by a kmalloc (which is significantly faster).  Instead of changing this
> open-coded implementation, just use kvmalloc().
> 
> This improves the allocation speed of vmalloc(4MB) by approximately
> 5% in our benchmark.  It's still dominated by the 1024 calls to
> alloc_pages_node(), which will be the subject of a later patch.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>

Acked-by: David Rientjes <rientjes@...gle.com>