Messages in this thread Patch in this message |  | | | Date | Tue, 17 Jun 1997 14:36:17 +0200 | | From | "Dr. Werner Fink" <> | | Subject | Re: buffers vs. pages vs. kernel speed |
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A few hours ago I wrote:
> Hi Dave, > > I've added one small change to your patch in __get_free_pages > (mm/page_alloc.c): > Maybe it's better to handle GFP_BUFFER the same way as GFP_NFS to > avoid heavy swapping if a process needs buffer but allow swapping if > necessary. This change makes the mouse much more usable. > > One point I've removed from a previous patch I've made is the skipping > of buffer pages if shrink_mmap is called in the case of getting free > buffer pages. > > This patch is against pre-patch-2.0.31-2 and includes your patch. > > Werner
[ ... patch deleted ...]
There is a typo in the patch above, please try the following one.
Werner
--------------------------------------------------------------------- diff -urN linux-2.0.31-clean/fs/buffer.c linux/fs/buffer.c --- linux-2.0.31-clean/fs/buffer.c Tue Jun 10 12:58:46 1997 +++ linux/fs/buffer.c Tue Jun 17 12:14:06 1997 @@ -660,20 +660,15 @@ goto repeat; } - /* Too bad, that was not enough. Try a little harder to grow some. */ - - if (nr_free_pages > min_free_pages + 5) { - if (grow_buffers(GFP_BUFFER, size)) { - needed -= PAGE_SIZE; - goto repeat; - }; - } + /* Too bad, that was not enough. Try a little harder to grow some. + * and repeat until we find something good + */ - /* and repeat until we find something good */ - if (grow_buffers(GFP_ATOMIC, size)) + if (grow_buffers(GFP_BUFFER, size)) needed -= PAGE_SIZE; else wakeup_bdflush(1); + goto repeat; } @@ -931,11 +926,16 @@ * This is critical. We can't swap out pages to get * more buffer heads, because the swap-out may need * more buffer-heads itself. Thus GFP_ATOMIC. + * + * This is no longer true, it is GFP_BUFFER again, the + * swapping code now knows not to perform I/O when that + * GFP level is specified... -DaveM */ + /* we now use kmalloc() here instead of gfp as we want to be able to easily release buffer heads - they took up quite a bit of memory (tridge) */ - bh = (struct buffer_head *) kmalloc(sizeof(*bh),GFP_ATOMIC); + bh = (struct buffer_head *) kmalloc(sizeof(*bh),GFP_BUFFER); if (bh) { put_unused_buffer_head(bh); nr_buffer_heads++; diff -urN linux-2.0.31-clean/include/linux/mm.h linux/include/linux/mm.h --- linux-2.0.31-clean/include/linux/mm.h Sat Mar 29 01:08:17 1997 +++ linux/include/linux/mm.h Mon Jun 16 22:26:25 1997 @@ -295,7 +295,7 @@ /* filemap.c */ extern unsigned long page_unuse(unsigned long); -extern int shrink_mmap(int, int); +extern int shrink_mmap(int, int, int); extern void truncate_inode_pages(struct inode *, unsigned long); #define GFP_BUFFER 0x00 diff -urN linux-2.0.31-clean/mm/filemap.c linux/mm/filemap.c --- linux-2.0.31-clean/mm/filemap.c Tue Jun 10 12:58:48 1997 +++ linux/mm/filemap.c Mon Jun 16 22:19:32 1997 @@ -127,7 +127,7 @@ } } -int shrink_mmap(int priority, int dma) +int shrink_mmap(int priority, int dma, int gfp_level) { static int clock = 0; struct page * page; diff -urN linux-2.0.31-clean/mm/page_alloc.c linux/mm/page_alloc.c --- linux-2.0.31-clean/mm/page_alloc.c Sat Aug 17 20:19:29 1996 +++ linux/mm/page_alloc.c Tue Jun 17 12:13:24 1997 @@ -202,9 +202,14 @@ priority = GFP_ATOMIC; } } - reserved_pages = 5; - if (priority != GFP_NFS) - reserved_pages = min_free_pages; + switch (priority) { + case GFP_NFS: + case GFP_BUFFER: + reserved_pages = 5; + break; + default: + reserved_pages = min_free_pages; + } save_flags(flags); repeat: cli(); @@ -214,7 +219,7 @@ return 0; } restore_flags(flags); - if (priority != GFP_BUFFER && try_to_free_page(priority, dma, 1)) + if (try_to_free_page(priority, dma, 1)) goto repeat; return 0; } @@ -264,11 +269,11 @@ /* * select nr of pages we try to keep free for important stuff - * with a minimum of 16 pages. This is totally arbitrary + * with a minimum of 24 pages. This is totally arbitrary */ i = (end_mem - PAGE_OFFSET) >> (PAGE_SHIFT+7); - if (i < 16) - i = 16; + if (i < 24) + i = 24; min_free_pages = i; free_pages_low = i + (i>>1); free_pages_high = i + i; diff -urN linux-2.0.31-clean/mm/vmscan.c linux/mm/vmscan.c --- linux-2.0.31-clean/mm/vmscan.c Sat Dec 14 13:24:31 1996 +++ linux/mm/vmscan.c Mon Jun 16 20:11:47 1997 @@ -68,7 +68,7 @@ * have died while we slept). */ static inline int try_to_swap_out(struct task_struct * tsk, struct vm_area_struct* vma, - unsigned long address, pte_t * page_table, int dma, int wait) + unsigned long address, pte_t * page_table, int dma, int wait, int can_do_io) { pte_t pte; unsigned long entry; @@ -100,6 +100,8 @@ if (page_map->age) return 0; if (pte_dirty(pte)) { + if(!can_do_io) + return 0; if (vma->vm_ops && vma->vm_ops->swapout) { pid_t pid = tsk->pid; vma->vm_mm->rss--; @@ -157,7 +159,8 @@ */ static inline int swap_out_pmd(struct task_struct * tsk, struct vm_area_struct * vma, - pmd_t *dir, unsigned long address, unsigned long end, int dma, int wait) + pmd_t *dir, unsigned long address, unsigned long end, int dma, int wait, + int can_do_io) { pte_t * pte; unsigned long pmd_end; @@ -179,7 +182,7 @@ do { int result; tsk->swap_address = address + PAGE_SIZE; - result = try_to_swap_out(tsk, vma, address, pte, dma, wait); + result = try_to_swap_out(tsk, vma, address, pte, dma, wait, can_do_io); if (result) return result; address += PAGE_SIZE; @@ -189,7 +192,8 @@ } static inline int swap_out_pgd(struct task_struct * tsk, struct vm_area_struct * vma, - pgd_t *dir, unsigned long address, unsigned long end, int dma, int wait) + pgd_t *dir, unsigned long address, unsigned long end, int dma, int wait, + int can_do_io) { pmd_t * pmd; unsigned long pgd_end; @@ -209,7 +213,7 @@ end = pgd_end; do { - int result = swap_out_pmd(tsk, vma, pmd, address, end, dma, wait); + int result = swap_out_pmd(tsk, vma, pmd, address, end, dma, wait, can_do_io); if (result) return result; address = (address + PMD_SIZE) & PMD_MASK; @@ -219,7 +223,7 @@ } static int swap_out_vma(struct task_struct * tsk, struct vm_area_struct * vma, - pgd_t *pgdir, unsigned long start, int dma, int wait) + pgd_t *pgdir, unsigned long start, int dma, int wait, int can_do_io) { unsigned long end; @@ -230,7 +234,7 @@ end = vma->vm_end; while (start < end) { - int result = swap_out_pgd(tsk, vma, pgdir, start, end, dma, wait); + int result = swap_out_pgd(tsk, vma, pgdir, start, end, dma, wait, can_do_io); if (result) return result; start = (start + PGDIR_SIZE) & PGDIR_MASK; @@ -239,7 +243,7 @@ return 0; } -static int swap_out_process(struct task_struct * p, int dma, int wait) +static int swap_out_process(struct task_struct * p, int dma, int wait, int can_do_io) { unsigned long address; struct vm_area_struct* vma; @@ -260,7 +264,7 @@ address = vma->vm_start; for (;;) { - int result = swap_out_vma(p, vma, pgd_offset(p->mm, address), address, dma, wait); + int result = swap_out_vma(p, vma, pgd_offset(p->mm, address), address, dma, wait, can_do_io); if (result) return result; vma = vma->vm_next; @@ -272,7 +276,7 @@ return 0; } -static int swap_out(unsigned int priority, int dma, int wait) +static int swap_out(unsigned int priority, int dma, int wait, int gfp_level) { static int swap_task; int loop, counter; @@ -311,7 +315,7 @@ } if (!--p->swap_cnt) swap_task++; - switch (swap_out_process(p, dma, wait)) { + switch (swap_out_process(p, dma, wait, gfp_level != GFP_BUFFER)) { case 0: if (p->swap_cnt) swap_task++; @@ -330,33 +334,61 @@ * to be. This works out OK, because we now do proper aging on page * contents. */ +#define TRIED_SMMAP 0x1 +#define TRIED_SSWAP 0x2 +#define TRIED_SWOUT 0x4 int try_to_free_page(int priority, int dma, int wait) { static int state = 0; int i=6; - int stop; + int stop, tried_mask = 0; + int old_stop, old_state; /* we don't try as hard if we're not waiting.. */ stop = 3; if (wait) stop = 0; + old_stop = stop; + old_state = state; switch (state) { do { case 0: - if (shrink_mmap(i, dma)) + /* Don't worry here for the GFP_BUFFER case, shrink_mmap never + * tries to write dirty things out... + */ + tried_mask |= TRIED_SMMAP; + if (shrink_mmap(i, dma, priority)) { + state = 1; return 1; - state = 1; + } case 1: - if (shm_swap(i, dma)) - return 1; - state = 2; + /* shm_swap must always perform some I/O if it succeeds + * in finding things to free up, so don't waste any time + * if we are trying to get some buffer heads... + */ + if (priority != GFP_BUFFER) { + tried_mask |= TRIED_SSWAP; + if(shm_swap(i, dma)) { + state = 2; + return 1; + } + } default: - if (swap_out(i, dma, wait)) + tried_mask |= TRIED_SWOUT; + if (swap_out(i, dma, wait, priority)) { + state = 0; return 1; - state = 0; + } i--; } while ((i - stop) >= 0); } + printk("try_to_free_page(%d,%d,%d): FAIL try(%s:%s:%s) state[o(%d):n(%d)] " + "stop[o(%d):n(%d)]\n", priority, dma, wait, + tried_mask & TRIED_SMMAP ? "shrink_mmap" : "", + tried_mask & TRIED_SSWAP ? "shm_swap" : "", + tried_mask & TRIED_SWOUT ? "swap_out" : "", + old_state, state, old_stop, stop); + state = 0; return 0; }
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