This patch seems to significantly improve the interactive
performance of 2.2.16. Without the patch XMMS and the mouse
pointer will stop responding for seconds at a time while running
Bonnie. With the patch everything is smooth.
I timed a kernel compile with -j 20 to test the cost of the
aging. It does not seem to make a significant difference (3
seconds slower). Bonnie reports slightly higher IO figures
with the patch. I don't think the change is significant.
Comments appreciated.
Neil
-- "If you're a great programmer, you make all the routines depend on each other, so little mistakes can really hurt you." -- Bill Gates, ca. 1985.diff -ru linux-2.2/include/linux/mm.h linux-age/include/linux/mm.h --- linux-2.2/include/linux/mm.h Thu Jun 8 00:30:02 2000 +++ linux-age/include/linux/mm.h Thu Jun 8 01:49:42 2000 @@ -129,7 +129,11 @@ struct wait_queue *wait; struct page **pprev_hash; struct buffer_head * buffers; + int age; } mem_map_t; + +#define PAGE_AGE_INITIAL 1 /* age for pages just mapped */ +#define PAGE_AGE_YOUNG 2 /* age for pages recently referenced */ /* Page flag bit values */ #define PG_locked 0 diff -ru linux-2.2/mm/filemap.c linux-age/mm/filemap.c --- linux-2.2/mm/filemap.c Thu Jun 8 00:30:26 2000 +++ linux-age/mm/filemap.c Thu Jun 8 01:44:16 2000 @@ -147,8 +147,6 @@ page = mem_map + clock; do { - int referenced; - /* This works even in the presence of PageSkip because * the first two entries at the beginning of a hole will * be marked, not just the first. @@ -165,12 +163,20 @@ clock = page - mem_map; } + if (test_and_clear_bit(PG_referenced, &page->flags)) { + page->age = PAGE_AGE_YOUNG; + continue; + } + + if (page->age > 0) { + page->age--; + continue; + } + /* We can't free pages unless there's just one user */ if (atomic_read(&page->count) != 1) continue; - referenced = test_and_clear_bit(PG_referenced, &page->flags); - if (PageLocked(page)) continue; @@ -179,20 +185,11 @@ count--; - /* - * Is it a page swap page? If so, we want to - * drop it if it is no longer used, even if it - * were to be marked referenced.. - */ + /* Is it a page swap page? Drop it, its old. */ if (PageSwapCache(page)) { - if (referenced && swap_count(page->offset) != 1) - continue; delete_from_swap_cache(page); return 1; } - - if (referenced) - continue; /* Is it a buffer page? */ if (page->buffers) { diff -ru linux-2.2/mm/page_alloc.c linux-age/mm/page_alloc.c --- linux-2.2/mm/page_alloc.c Thu Jun 8 00:30:26 2000 +++ linux-age/mm/page_alloc.c Thu Jun 8 01:49:50 2000 @@ -129,6 +129,7 @@ if (PageSwapCache(page)) panic ("Freeing swap cache page"); page->flags &= ~(1 << PG_referenced); + page->age = PAGE_AGE_INITIAL; free_pages_ok(page - mem_map, order, PageDMA(page) ? 1 : 0); return; }
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This archive was generated by hypermail 2b29 : Thu Jun 15 2000 - 21:00:14 EST