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Date: Tue, 16 Feb 2010 16:05:04 +0900 (JST) From: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com> To: Mel Gorman <mel@....ul.ie> Cc: kosaki.motohiro@...fujitsu.com, Andrea Arcangeli <aarcange@...hat.com>, Christoph Lameter <cl@...ux-foundation.org>, Adam Litke <agl@...ibm.com>, Avi Kivity <avi@...hat.com>, David Rientjes <rientjes@...gle.com>, linux-kernel@...r.kernel.org, linux-mm@...ck.org Subject: Re: [PATCH 01/12] mm: Document /proc/pagetypeinfo > The memory compaction patches add details to pagetypeinfo that are not > obvious and need to be documented. In preparation for this, document > what is already in /proc/pagetypeinfo. > > Signed-off-by: Mel Gorman <mel@....ul.ie> Looks nicer. Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com> > --- > Documentation/filesystems/proc.txt | 45 +++++++++++++++++++++++++++++++++++- > 1 files changed, 44 insertions(+), 1 deletions(-) > > diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt > index 0d07513..1829dfb 100644 > --- a/Documentation/filesystems/proc.txt > +++ b/Documentation/filesystems/proc.txt > @@ -430,6 +430,7 @@ Table 1-5: Kernel info in /proc > modules List of loaded modules > mounts Mounted filesystems > net Networking info (see text) > + pagetypeinfo Additional page allocator information (see text) (2.5) > partitions Table of partitions known to the system > pci Deprecated info of PCI bus (new way -> /proc/bus/pci/, > decoupled by lspci (2.4) > @@ -584,7 +585,7 @@ Node 0, zone DMA 0 4 5 4 4 3 ... > Node 0, zone Normal 1 0 0 1 101 8 ... > Node 0, zone HighMem 2 0 0 1 1 0 ... > > -Memory fragmentation is a problem under some workloads, and buddyinfo is a > +External fragmentation is a problem under some workloads, and buddyinfo is a > useful tool for helping diagnose these problems. Buddyinfo will give you a > clue as to how big an area you can safely allocate, or why a previous > allocation failed. > @@ -594,6 +595,48 @@ available. In this case, there are 0 chunks of 2^0*PAGE_SIZE available in > ZONE_DMA, 4 chunks of 2^1*PAGE_SIZE in ZONE_DMA, 101 chunks of 2^4*PAGE_SIZE > available in ZONE_NORMAL, etc... > > +More information relevant to external fragmentation can be found in > +pagetypeinfo. > + > +> cat /proc/pagetypeinfo > +Page block order: 9 > +Pages per block: 512 > + > +Free pages count per migrate type at order 0 1 2 3 4 5 6 7 8 9 10 > +Node 0, zone DMA, type Unmovable 0 0 0 1 1 1 1 1 1 1 0 > +Node 0, zone DMA, type Reclaimable 0 0 0 0 0 0 0 0 0 0 0 > +Node 0, zone DMA, type Movable 1 1 2 1 2 1 1 0 1 0 2 > +Node 0, zone DMA, type Reserve 0 0 0 0 0 0 0 0 0 1 0 > +Node 0, zone DMA, type Isolate 0 0 0 0 0 0 0 0 0 0 0 > +Node 0, zone DMA32, type Unmovable 103 54 77 1 1 1 11 8 7 1 9 > +Node 0, zone DMA32, type Reclaimable 0 0 2 1 0 0 0 0 1 0 0 > +Node 0, zone DMA32, type Movable 169 152 113 91 77 54 39 13 6 1 452 > +Node 0, zone DMA32, type Reserve 1 2 2 2 2 0 1 1 1 1 0 > +Node 0, zone DMA32, type Isolate 0 0 0 0 0 0 0 0 0 0 0 > + > +Number of blocks type Unmovable Reclaimable Movable Reserve Isolate > +Node 0, zone DMA 2 0 5 1 0 > +Node 0, zone DMA32 41 6 967 2 0 > + > +Fragmentation avoidance in the kernel works by grouping pages of different > +migrate types into the same contiguous regions of memory called page blocks. > +A page block is typically the size of the default hugepage size e.g. 2MB on > +X86-64. By keeping pages grouped based on their ability to move, the kernel > +can reclaim pages within a page block to satisfy a high-order allocation. > + > +The pagetypinfo begins with information on the size of a page block. It > +then gives the same type of information as buddyinfo except broken down > +by migrate-type and finishes with details on how many page blocks of each > +type exist. > + > +If min_free_kbytes has been tuned correctly (recommendations made by hugeadm > +from libhugetlbfs http://sourceforge.net/projects/libhugetlbfs/), one can > +make an estimate of the likely number of huge pages that can be allocated > +at a given point in time. All the "Movable" blocks should be allocatable > +unless memory has been mlock()'d. Some of the Reclaimable blocks should > +also be allocatable although a lot of filesystem metadata may have to be > +reclaimed to achieve this. > + > .............................................................................. > > meminfo: > -- > 1.6.5 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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