Commit c07161d8 authored by Nick Piggin's avatar Nick Piggin Committed by Linus Torvalds

[PATCH] mm: tune the page allocator thresholds

without patch:
      pages_min   pages_low   pages_high
dma        4          8          12
normal   234        468         702
high     128        256         384

with patch:
      pages_min   pages_low   pages_high
dma       17         21          25
normal   939       1173        1408
high     128        160         192

without patch:
                             | GFP_KERNEL        | GFP_ATOMIC
allocate immediately         |   9 dma, 469 norm |  9 dma, 469 norm
allocate after waking kswapd |   5 dma, 234 norm |  3 dma,  88 norm
allocate after synch reclaim |   5 dma, 234 norm |  n/a

with patch:
                             | GFP_KERNEL         | GFP_ATOMIC
allocate immediately         |  22 dma, 1174 norm | 22 dma, 1174 norm
allocate after waking kswapd |  18 dma,  940 norm |  6 dma,  440 norm
allocate after synch reclaim |  18 dma,  940 norm |  n/a

So the buffer between GFP_KERNEL and GFP_ATOMIC allocations is:

2.6.8      | 465 dma, 117 norm, 582 tot = 2328K
2.6.10-rc  |   2 dma, 146 norm, 148 tot =  592K
patch      |  12 dma, 500 norm, 512 tot = 2048K

Which is getting pretty good.

kswap starts at:
2.6.8     477 dma, 496 norm, 973 total
2.6.10-rc   8 dma, 468 norm, 476 total
patched    17 dma, 939 norm, 956 total

So in terms of total pages, that's looking similar to 2.6.8.
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent ce57094b
...@@ -1945,8 +1945,12 @@ static void setup_per_zone_pages_min(void) ...@@ -1945,8 +1945,12 @@ static void setup_per_zone_pages_min(void)
lowmem_pages; 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); spin_unlock_irqrestore(&zone->lru_lock, flags);
} }
} }
...@@ -1955,24 +1959,25 @@ static void setup_per_zone_pages_min(void) ...@@ -1955,24 +1959,25 @@ static void setup_per_zone_pages_min(void)
* Initialise min_free_kbytes. * Initialise min_free_kbytes.
* *
* For small machines we want it small (128k min). For large machines * 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 * 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 * which yields
* *
* 16MB: 128k * 16MB: 512k
* 32MB: 181k * 32MB: 724k
* 64MB: 256k * 64MB: 1024k
* 128MB: 362k * 128MB: 1448k
* 256MB: 512k * 256MB: 2048k
* 512MB: 724k * 512MB: 2896k
* 1024MB: 1024k * 1024MB: 4096k
* 2048MB: 1448k * 2048MB: 5792k
* 4096MB: 2048k * 4096MB: 8192k
* 8192MB: 2896k * 8192MB: 11584k
* 16384MB: 4096k * 16384MB: 16384k
*/ */
static int __init init_per_zone_pages_min(void) static int __init init_per_zone_pages_min(void)
{ {
...@@ -1980,11 +1985,11 @@ static int __init init_per_zone_pages_min(void) ...@@ -1980,11 +1985,11 @@ static int __init init_per_zone_pages_min(void)
lowmem_kbytes = nr_free_buffer_pages() * (PAGE_SIZE >> 10); 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) if (min_free_kbytes < 128)
min_free_kbytes = 128; min_free_kbytes = 128;
if (min_free_kbytes > 16384) if (min_free_kbytes > 65536)
min_free_kbytes = 16384; min_free_kbytes = 65536;
setup_per_zone_pages_min(); setup_per_zone_pages_min();
setup_per_zone_protection(); setup_per_zone_protection();
return 0; return 0;
......
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