Messages in this thread Patch in this message | | | Date | Mon, 23 Nov 1998 21:53:59 +0100 | From | "Dr. Werner Fink" <> | Subject | Running 2.1.129 at extrem load [patch] (Was: Linux-2.1.129..) |
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[...]
> > Maybe we even want to keep a 3:1 ratio or something like that for > > mapped:swap_cached pages and a semi- FIFO reclamation of swap cached > > pages so we can simulate a bit of (very cheap) page aging. > > I will just restate my profound conviction that any VM balancing which > works by imposing precalculated limits on resources is fundamentally > wrong. > > Cheers, > Stephen
I've done some simply test and worked out some changes (patch enclosed). Starting with a plain 2.1.129 I've run a simple stress situation:
* 64MB ram + 128 MB swap * Under X11 (fvwm2) * xload * xosview * xterm running top * xterm running tail -f /var/log/warn /var/log/messages * xterm compiling 2.0.36 sources with: while true; do make clean; make -j || break ; done * xterm compiling 2.1.129 sources with: while true; do make clean; make MAKE='make -j5' || break ; done
.. clearly all together. Load goes upto 30 and higher and random SIGBUS to random processes occurs (in best case the X server was signaled which makes the system usable again).
I've add some changes:
* changed the position of deleting pages from swap cache in mm/filemap.c::shrink_one_page() * add a simple repeat case in mm/page_alloc.c::__get_free_pages() if we wait on low priority pages (aka GFP_USER). * don't let mm/vmscan.c::try_to_free_pages() scan to much. * add a simple age scheme for recently swapped in pages. (The condition, e.g. a bigger rss window is changeable).
The random SIGBUS disappears and the system seems more usable which means only loads over 35 and higher makes the system only temporarily unusable.
Werner
-------------------------------------------------------------------- diff -urN linux-2.1.129/include/linux/mm.h linux/include/linux/mm.h --- linux-2.1.129/include/linux/mm.h Thu Nov 19 20:49:37 1998 +++ linux/include/linux/mm.h Mon Nov 23 14:53:14 1998 @@ -117,7 +117,7 @@ unsigned long offset; struct page *next_hash; atomic_t count; - unsigned int unused; + unsigned int lifetime; unsigned long flags; /* atomic flags, some possibly updated asynchronously */ struct wait_queue *wait; struct page **pprev_hash; diff -urN linux-2.1.129/ipc/shm.c linux/ipc/shm.c --- linux-2.1.129/ipc/shm.c Sun Oct 18 00:52:18 1998 +++ linux/ipc/shm.c Mon Nov 23 15:14:00 1998 @@ -15,6 +15,7 @@ #include <linux/stat.h> #include <linux/malloc.h> #include <linux/swap.h> +#include <linux/swapctl.h> #include <linux/smp.h> #include <linux/smp_lock.h> #include <linux/init.h> @@ -656,6 +657,7 @@ pte = __pte(shp->shm_pages[idx]); if (!pte_present(pte)) { + int old_rss = shm_rss; unsigned long page = get_free_page(GFP_KERNEL); if (!page) { oom(current); @@ -677,6 +679,16 @@ shm_swp--; } shm_rss++; + + /* Increase life time of the page */ + mem_map[MAP_NR(page)].lifetime = 0; + if (old_rss == 0) + current->dec_flt++; + if (current->dec_flt > 3) { + mem_map[MAP_NR(page)].lifetime = 3 * PAGE_ADVANCE; + current->dec_flt = 0; + } + pte = pte_mkdirty(mk_pte(page, PAGE_SHARED)); shp->shm_pages[idx] = pte_val(pte); } else diff -urN linux-2.1.129/mm/filemap.c linux/mm/filemap.c --- linux-2.1.129/mm/filemap.c Thu Nov 19 20:44:18 1998 +++ linux/mm/filemap.c Mon Nov 23 13:38:47 1998 @@ -167,15 +167,14 @@ case 1: /* is it a swap-cache or page-cache page? */ if (page->inode) { - /* Throw swap-cache pages away more aggressively */ - if (PageSwapCache(page)) { - delete_from_swap_cache(page); - return 1; - } if (test_and_clear_bit(PG_referenced, &page->flags)) break; if (pgcache_under_min()) break; + if (PageSwapCache(page)) { + delete_from_swap_cache(page); + return 1; + } remove_inode_page(page); return 1; } diff -urN linux-2.1.129/mm/page_alloc.c linux/mm/page_alloc.c --- linux-2.1.129/mm/page_alloc.c Thu Nov 19 20:44:18 1998 +++ linux/mm/page_alloc.c Mon Nov 23 19:31:10 1998 @@ -236,6 +236,7 @@ unsigned long __get_free_pages(int gfp_mask, unsigned long order) { unsigned long flags; + int loop = 0; if (order >= NR_MEM_LISTS) goto nopage; @@ -262,6 +263,7 @@ goto nopage; } } +repeat: spin_lock_irqsave(&page_alloc_lock, flags); RMQUEUE(order, (gfp_mask & GFP_DMA)); spin_unlock_irqrestore(&page_alloc_lock, flags); @@ -274,6 +276,8 @@ if (gfp_mask & __GFP_WAIT) { current->policy |= SCHED_YIELD; schedule(); + if (!loop++ && nr_free_pages > freepages.low) + goto repeat; } nopage: @@ -380,6 +384,7 @@ { unsigned long page; struct page *page_map; + int shared, old_rss = vma->vm_mm->rss; page_map = read_swap_cache(entry); @@ -399,8 +404,18 @@ vma->vm_mm->rss++; tsk->min_flt++; swap_free(entry); + shared = is_page_shared(page_map); - if (!write_access || is_page_shared(page_map)) { + /* Increase life time of the page */ + page_map->lifetime = 0; + if (old_rss == 0) + tsk->dec_flt++; + if (tsk->dec_flt > 3) { + page_map->lifetime = (shared ? 2 : 5) * PAGE_ADVANCE; + tsk->dec_flt = 0; + } + + if (!write_access || shared) { set_pte(page_table, mk_pte(page, vma->vm_page_prot)); return; } diff -urN linux-2.1.129/mm/vmscan.c linux/mm/vmscan.c --- linux-2.1.129/mm/vmscan.c Thu Nov 19 20:44:18 1998 +++ linux/mm/vmscan.c Mon Nov 23 19:34:21 1998 @@ -131,12 +131,21 @@ return 0; } + /* life time decay */ + if (page_map->lifetime > PAGE_DECLINE) + page_map->lifetime -= PAGE_DECLINE; + else + page_map->lifetime = 0; + if (page_map->lifetime) + return 0; + if (pte_dirty(pte)) { if (vma->vm_ops && vma->vm_ops->swapout) { pid_t pid = tsk->pid; vma->vm_mm->rss--; - if (vma->vm_ops->swapout(vma, address - vma->vm_start + vma->vm_offset, page_table)) + if (vma->vm_ops->swapout(vma, address - vma->vm_start + vma->vm_offset, page_table)) { kill_proc(pid, SIGBUS, 1); + } } else { /* * This is a dirty, swappable page. First of all, @@ -561,6 +570,7 @@ int try_to_free_pages(unsigned int gfp_mask, int count) { int retval = 1; + int is_dma = (gfp_mask & __GFP_DMA); lock_kernel(); if (!(current->flags & PF_MEMALLOC)) { @@ -568,6 +578,8 @@ do { retval = do_try_to_free_page(gfp_mask); if (!retval) + break; + if (!is_dma && nr_free_pages > freepages.high + SWAP_CLUSTER_MAX) break; count--; } while (count > 0); - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/
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