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authorLinus Torvalds <torvalds@woody.linux-foundation.org>2007-01-29 19:37:38 -0500
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-01-29 19:37:38 -0500
commitdc6e29da9162fa8fa2a9e798569c0f6e87975614 (patch)
tree9d1e9c8095ea4fbc7d528a63d4b21e32e44a70a9 /mm/page-writeback.c
parent5263bf65d6342e12ab716db8e529501670979321 (diff)
Fix balance_dirty_page() calculations with CONFIG_HIGHMEM
This makes balance_dirty_page() always base its calculations on the amount of non-highmem memory in the machine, rather than try to base it on total memory and then falling back on non-highmem memory if the mapping it was writing wasn't highmem capable. This not only fixes a situation where two different writers can have wildly different notions about what is a "balanced" dirty state, but it also means that people with highmem machines don't run into an OOM situation when regular memory fills up with dirty pages. We used to try to handle the latter case by scaling down the dirty_ratio if the machine had a lot of highmem pages in page_writeback_init(), but it wasn't aggressive enough for some situations, and since basing the dirty ratio on highmem memory was broken in the first place, let's just stop doing so. (A variation of this theme fixed Justin Piszcz's OOM problem when copying an 18GB file on a RAID setup). Acked-by: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Justin Piszcz <jpiszcz@lucidpixels.com> Cc: Andrew Morton <akpm@osdl.org> Cc: Neil Brown <neilb@suse.de> Cc: Ingo Molnar <mingo@elte.hu> Cc: Randy Dunlap <rdunlap@xenotime.net> Cc: Christoph Lameter <clameter@sgi.com> Cc: Jens Axboe <jens.axboe@oracle.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Adrian Bunk <bunk@stusta.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/page-writeback.c')
-rw-r--r--mm/page-writeback.c41
1 files changed, 18 insertions, 23 deletions
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 1d2fc89ca56d..be0efbde4994 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -133,11 +133,9 @@ get_dirty_limits(long *pbackground, long *pdirty,
133 133
134#ifdef CONFIG_HIGHMEM 134#ifdef CONFIG_HIGHMEM
135 /* 135 /*
136 * If this mapping can only allocate from low memory, 136 * We always exclude high memory from our count.
137 * we exclude high memory from our count.
138 */ 137 */
139 if (mapping && !(mapping_gfp_mask(mapping) & __GFP_HIGHMEM)) 138 available_memory -= totalhigh_pages;
140 available_memory -= totalhigh_pages;
141#endif 139#endif
142 140
143 141
@@ -526,28 +524,25 @@ static struct notifier_block __cpuinitdata ratelimit_nb = {
526}; 524};
527 525
528/* 526/*
529 * If the machine has a large highmem:lowmem ratio then scale back the default 527 * Called early on to tune the page writeback dirty limits.
530 * dirty memory thresholds: allowing too much dirty highmem pins an excessive 528 *
531 * number of buffer_heads. 529 * We used to scale dirty pages according to how total memory
530 * related to pages that could be allocated for buffers (by
531 * comparing nr_free_buffer_pages() to vm_total_pages.
532 *
533 * However, that was when we used "dirty_ratio" to scale with
534 * all memory, and we don't do that any more. "dirty_ratio"
535 * is now applied to total non-HIGHPAGE memory (by subtracting
536 * totalhigh_pages from vm_total_pages), and as such we can't
537 * get into the old insane situation any more where we had
538 * large amounts of dirty pages compared to a small amount of
539 * non-HIGHMEM memory.
540 *
541 * But we might still want to scale the dirty_ratio by how
542 * much memory the box has..
532 */ 543 */
533void __init page_writeback_init(void) 544void __init page_writeback_init(void)
534{ 545{
535 long buffer_pages = nr_free_buffer_pages();
536 long correction;
537
538 correction = (100 * 4 * buffer_pages) / vm_total_pages;
539
540 if (correction < 100) {
541 dirty_background_ratio *= correction;
542 dirty_background_ratio /= 100;
543 vm_dirty_ratio *= correction;
544 vm_dirty_ratio /= 100;
545
546 if (dirty_background_ratio <= 0)
547 dirty_background_ratio = 1;
548 if (vm_dirty_ratio <= 0)
549 vm_dirty_ratio = 1;
550 }
551 mod_timer(&wb_timer, jiffies + dirty_writeback_interval); 546 mod_timer(&wb_timer, jiffies + dirty_writeback_interval);
552 writeback_set_ratelimit(); 547 writeback_set_ratelimit();
553 register_cpu_notifier(&ratelimit_nb); 548 register_cpu_notifier(&ratelimit_nb);