Messages in this thread Patch in this message | | | Date | Wed, 10 Nov 2004 15:24:10 +1100 | From | Nick Piggin <> | Subject | Re: 2.6.10-rc1-mm4 -1 EAGAIN after allocation failure was: Re: Kernel 2.6.9 Multiple Page Allocation Failures |
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Stefan Schmidt wrote:
>On Tue, Nov 09, 2004 at 05:39:20PM -0800, Andrew Morton wrote: > >>Well you've definitely used up all the memory which is available for atomic >>allocations. Are you using an increased /proc/sys/vm/min_free_kbytes there? >> >Yes, vm.min_free_kbytes=8192. >For other vm-settings find sysctl.conf attached. > >Netdev: tg3 BCM5704r03, TSO off, ~32kpps rx, ~35kpps tx, ~2 rx errors/s > > >>As for the application collapse: dunno. Maybe networking broke. It would >>be interesting to test Linus's current tree, at >>ftp://ftp.kernel.org/pub/linux/kernel/v2.6/snapshots/patch-2.6.10-rc1-bk19.gz >> >Will try that tomorrow. Would you suggest printing out show_free_areas(); >there too? I don't know what kind of an overhead that will generate on >subsequent stack traces. > >
Stefan, Can you try the following patch, please? It is diffed against 2.6.10-rc1, but I think it should apply to -mm kernels as well.
Basically 2.6.8 and earlier kernels had some quirks in the page allocator that would allow for example, a large portion of "DMA" memory to be reserved for network memory allocations (atomic allocations). After 'fixing' this problem, 2.6.9 is effectively left with about a quarter the amount of memory reserved for network allocations compared with 2.6.8.
The following patch roughly restores parity there. Thanks.
Nick
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linux-2.6-npiggin/mm/page_alloc.c | 41 +++++++++++++++++++++----------------- 1 files changed, 23 insertions(+), 18 deletions(-)
diff -puN mm/page_alloc.c~mm-restore-atomic-buffer mm/page_alloc.c --- linux-2.6/mm/page_alloc.c~mm-restore-atomic-buffer 2004-11-10 15:13:33.000000000 +1100 +++ linux-2.6-npiggin/mm/page_alloc.c 2004-11-10 14:57:54.000000000 +1100 @@ -1935,8 +1935,12 @@ static void setup_per_zone_pages_min(voi lowmem_pages; } - zone->pages_low = zone->pages_min * 2; - zone->pages_high = zone->pages_min * 3; + /* + * When interpreting these watermarks, just keep in mind that: + * zone->pages_min == (zone->pages_min * 4) / 4; + */ + zone->pages_low = (zone->pages_min * 5) / 4; + zone->pages_high = (zone->pages_min * 6) / 4; spin_unlock_irqrestore(&zone->lru_lock, flags); } } @@ -1945,24 +1949,25 @@ static void setup_per_zone_pages_min(voi * Initialise min_free_kbytes. * * For small machines we want it small (128k min). For large machines - * we want it large (16MB max). But it is not linear, because network + * we want it large (64MB max). But it is not linear, because network * bandwidth does not increase linearly with machine size. We use * - * min_free_kbytes = sqrt(lowmem_kbytes) + * min_free_kbytes = 4 * sqrt(lowmem_kbytes), for better accuracy: + * min_free_kbytes = sqrt(lowmem_kbytes * 16) * * which yields * - * 16MB: 128k - * 32MB: 181k - * 64MB: 256k - * 128MB: 362k - * 256MB: 512k - * 512MB: 724k - * 1024MB: 1024k - * 2048MB: 1448k - * 4096MB: 2048k - * 8192MB: 2896k - * 16384MB: 4096k + * 16MB: 512k + * 32MB: 724k + * 64MB: 1024k + * 128MB: 1448k + * 256MB: 2048k + * 512MB: 2896k + * 1024MB: 4096k + * 2048MB: 5792k + * 4096MB: 8192k + * 8192MB: 11584k + * 16384MB: 16384k */ static int __init init_per_zone_pages_min(void) { @@ -1970,11 +1975,11 @@ static int __init init_per_zone_pages_mi lowmem_kbytes = nr_free_buffer_pages() * (PAGE_SIZE >> 10); - min_free_kbytes = int_sqrt(lowmem_kbytes); + min_free_kbytes = int_sqrt(lowmem_kbytes * 16); if (min_free_kbytes < 128) min_free_kbytes = 128; - if (min_free_kbytes > 16384) - min_free_kbytes = 16384; + if (min_free_kbytes > 65536) + min_free_kbytes = 65536; setup_per_zone_pages_min(); setup_per_zone_protection(); return 0; _
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