From: Mel Gorman <mgorman@techsingularity.net>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Michal Hocko <mhocko@kernel.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Johannes Weiner <hannes@cmpxchg.org>
Subject: Re: [PATCH 1/2] mm, page_alloc: don't convert pfn to idx when merging
Date: Fri, 9 Dec 2016 19:40:27 +0000 [thread overview]
Message-ID: <20161209194027.4ltdedctw2fshuwe@techsingularity.net> (raw)
In-Reply-To: <e6f7ee3c-75ae-63a8-cde0-1d00e65cb973@suse.cz>
On Fri, Dec 09, 2016 at 07:32:22PM +0100, Vlastimil Babka wrote:
> > As a slight aside, I recently spotted that one of the largest overhead
> > in the bulk free path was in the page_is_buddy() checks so pretty much
> > anything that helps that is welcome.
>
> Interesting, the function shouldn't be doing really much on x86 without
> debug config options? We might try further optimize the zone equivalence
> checks, perhaps?
I don't have the data any more but IIRC, it was cache miss intensive and
I assumed at the time that it was checking cache cold struct pages
during merges.
At the time I was looking at splitting the per-cpu lists into irq and
non-irq so wasn't focused on the page_is_buddy part of the profile. It
just stuck in my mind as being surprisingly high.
--
Mel Gorman
SUSE Labs
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WARNING: multiple messages have this Message-ID (diff)
From: Mel Gorman <mgorman@techsingularity.net>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Michal Hocko <mhocko@kernel.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Johannes Weiner <hannes@cmpxchg.org>
Subject: Re: [PATCH 1/2] mm, page_alloc: don't convert pfn to idx when merging
Date: Fri, 9 Dec 2016 19:40:27 +0000 [thread overview]
Message-ID: <20161209194027.4ltdedctw2fshuwe@techsingularity.net> (raw)
In-Reply-To: <e6f7ee3c-75ae-63a8-cde0-1d00e65cb973@suse.cz>
On Fri, Dec 09, 2016 at 07:32:22PM +0100, Vlastimil Babka wrote:
> > As a slight aside, I recently spotted that one of the largest overhead
> > in the bulk free path was in the page_is_buddy() checks so pretty much
> > anything that helps that is welcome.
>
> Interesting, the function shouldn't be doing really much on x86 without
> debug config options? We might try further optimize the zone equivalence
> checks, perhaps?
I don't have the data any more but IIRC, it was cache miss intensive and
I assumed at the time that it was checking cache cold struct pages
during merges.
At the time I was looking at splitting the per-cpu lists into irq and
non-irq so wasn't focused on the page_is_buddy part of the profile. It
just stuck in my mind as being surprisingly high.
--
Mel Gorman
SUSE Labs
next prev parent reply other threads:[~2016-12-09 19:40 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-09 9:37 [PATCH 1/2] mm, page_alloc: don't convert pfn to idx when merging Vlastimil Babka
2016-12-09 9:37 ` Vlastimil Babka
2016-12-09 9:37 ` [PATCH 2/2] mm, page_alloc: avoid page_to_pfn() when merging buddies Vlastimil Babka
2016-12-09 9:37 ` Vlastimil Babka
2016-12-09 12:14 ` [PATCH 1/2] mm, page_alloc: don't convert pfn to idx when merging kbuild test robot
2016-12-09 12:14 ` kbuild test robot
2016-12-09 12:33 ` Vlastimil Babka
2016-12-09 12:33 ` Vlastimil Babka
2016-12-09 17:26 ` Mel Gorman
2016-12-09 17:26 ` Mel Gorman
2016-12-09 18:32 ` Vlastimil Babka
2016-12-09 18:32 ` Vlastimil Babka
2016-12-09 19:40 ` Mel Gorman [this message]
2016-12-09 19:40 ` Mel Gorman
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