From: Matthew Wilcox <willy-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
To: Tony Battersby <tonyb-vFAe+i1/wJI5UWNf+nJyDw@public.gmane.org>
Cc: linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org,
iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org,
Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>,
"linux-scsi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-scsi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Subject: Re: [PATCH v4 6/9] dmapool: improve scalability of dma_pool_free
Date: Mon, 12 Nov 2018 22:25:07 -0800 [thread overview]
Message-ID: <20181113062507.GQ21824@bombadil.infradead.org> (raw)
In-Reply-To: <4c3c25ab-5793-c394-9fe4-221b81805536-vFAe+i1/wJI5UWNf+nJyDw@public.gmane.org>
On Mon, Nov 12, 2018 at 10:44:40AM -0500, Tony Battersby wrote:
> dma_pool_free() scales poorly when the pool contains many pages because
> pool_find_page() does a linear scan of all allocated pages. Improve its
> scalability by replacing the linear scan with virt_to_page() and storing
> dmapool private data directly in 'struct page', thereby eliminating
> 'struct dma_page'. In big O notation, this improves the algorithm from
> O(n^2) to O(n) while also reducing memory usage.
>
> Thanks to Matthew Wilcox for the suggestion to use struct page.
>
> Signed-off-by: Tony Battersby <tonyb-vFAe+i1/wJI5UWNf+nJyDw@public.gmane.org>
Acked-by: Matthew Wilcox <willy-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
prev parent reply other threads:[~2018-11-13 6:25 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-12 15:44 [PATCH v4 6/9] dmapool: improve scalability of dma_pool_free Tony Battersby
[not found] ` <4c3c25ab-5793-c394-9fe4-221b81805536-vFAe+i1/wJI5UWNf+nJyDw@public.gmane.org>
2018-11-13 6:25 ` Matthew Wilcox [this message]
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