From: Andi Kleen <ak@suse.de>
To: Mel Gorman <mel@csn.ul.ie>
Cc: Andrew Morton <akpm@osdl.org>,
davej@codemonkey.org.uk, tony.luck@intel.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, bob.picco@hp.com,
linuxppc-dev@ozlabs.org
Subject: Re: [PATCH 0/5] Sizing zones and holes in an architecture independent manner V7
Date: Wed, 7 Jun 2006 12:16:24 +0200 [thread overview]
Message-ID: <200606071216.24640.ak@suse.de> (raw)
In-Reply-To: <Pine.LNX.4.64.0606071059480.20653@skynet.skynet.ie>
> Right now, x86_64 seems to be the only arch that accounts for the kernel
> image and memmap as holes so I would consider it to be unusual.
s/unusual/more advanced/
> For memory
> hot-add, new memmaps are allocated using kmalloc() and are not accounted
> for as holes.
At least in the standard (non sparsemem) hotadd they are accounted afaik.
> So, on x86_64, some memmaps are holes and others are not.
>
> Why is it a performance regression if the image and memmap is accounted
> for as holes? How are those regions different from any other kernel
> allocation or bootmem allocations for example which are not accounted as
> holes?
They are comparatively big and cannot be freed.
>If you are sure that it makes a measurable difference to performance,
There was at least one benchmark/use case where it made a significant
difference, can't remember the exact numbers though.
-Andi
next prev parent reply other threads:[~2006-06-07 10:16 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-06-06 13:47 [PATCH 0/5] Sizing zones and holes in an architecture independent manner V7 Mel Gorman
2006-06-06 13:47 ` [PATCH 1/5] Introduce mechanism for registering active regions of memory Mel Gorman
2006-06-06 13:47 ` [PATCH 2/5] Have Power use add_active_range() and free_area_init_nodes() Mel Gorman
2006-06-06 13:48 ` [PATCH 3/5] Have x86 use add_active_range() and free_area_init_nodes Mel Gorman
2006-06-06 13:48 ` [PATCH 4/5] Have x86_64 " Mel Gorman
2006-06-06 13:48 ` [PATCH 5/5] Have ia64 " Mel Gorman
2006-06-06 23:43 ` [PATCH 0/5] Sizing zones and holes in an architecture independent manner V7 Andrew Morton
2006-06-07 9:42 ` Mel Gorman
2006-06-07 9:45 ` Andi Kleen
2006-06-07 10:11 ` Mel Gorman
2006-06-07 10:16 ` Andi Kleen [this message]
2006-06-07 10:54 ` Mel Gorman
2006-06-07 15:20 ` Andi Kleen
2006-06-07 16:25 ` Mel Gorman
2006-06-09 12:57 ` Mel Gorman
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