Messages in this thread | | | Date | Wed, 13 Apr 2011 09:13:46 +0200 | From | Peter Kruse <> | Subject | Re: I have a blaze of 353 page allocation failures, all alike |
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Hello,
thanks for your replies, I appreciate that.
On 04/13/2011 03:34 AM, David Rientjes wrote: > On Tue, 12 Apr 2011, Christoph Lameter wrote: > >> The problem maybe that you have lots and lots of SCSI devices which >> consume ZONE_DMA memory for their control structures. I guess that is >> oversubscribing the 16M zone.
but there are only two devices:
# fdisk -l
Disk /dev/sda: 249.8 GB, 249865175040 bytes 255 heads, 63 sectors/track, 30377 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Disk identifier: 0x4ac39024
Device Boot Start End Blocks Id System /dev/sda1 1 13 104422 83 Linux /dev/sda2 14 30377 243898830 8e Linux LVM
WARNING: GPT (GUID Partition Table) detected on '/dev/sdb'! The util fdisk doesn't support GPT. Use GNU Parted.
Disk /dev/sdb: 37946.0 GB, 37946025574400 bytes 255 heads, 63 sectors/track, 4613341 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Disk identifier: 0x00000000
Disk /dev/sdb doesn't contain a valid partition table
> You can try to get more memory reserves specifically for lowmem in > ZONE_DMA by changing /proc/sys/vm/lowmem_reserve_ratio. The values are > ratios, so lowering the numbers will yield larger amounts of memory > reserves in ZONE_DMA for GFP_DMA allocations. Try lowering the non-zero > entries to 1 to reserve the entire zone for lowmem, assuming your system > has enough RAM for everything else you're running.
this server has 48GB - that should be enough.
> This will verify if ZONE_DMA is being depleted from the larger number of > SCSI devices. If you don't get any additional page allocation failures, > then check how much memory in ZONE_DMA is used at peak and that would be a > sane reserve ratio to use next time you restart the system.
Could that still be a problem if there are only two scsi devices?
Regards,
Peter
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