Hi,
here's a 3rd version of my patch to shrink_mmap(). This
version fixes most of the performance problems with
shrink_mmap() .. to make performance better big changes
will be needed. It also doesn't eliminate a possible race
condition (afaik Ben is working on that one) in shrink_mmap().
The patch does the following:
- remove possible race condition from truncate_inode_pages()
- don't age mapped pages, save the referenced bit for later
- put pages in the right place on the LRU queue
(thanks for the .prev hint, Andrea ;))
It has been tested under a fairly wide variety of (over)loaded
situations and performance has been good.
regards,
Rik
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--- linux-2.3.99-pre6-3/mm/filemap.c.orig Mon Apr 17 12:21:46 2000 +++ linux-2.3.99-pre6-3/mm/filemap.c Wed Apr 19 14:17:27 2000 @@ -149,11 +149,16 @@ /* page wholly truncated - free it */ if (offset >= start) { + if (TryLockPage(page)) { + spin_unlock(&pagecache_lock); + get_page(page); + wait_on_page(page); + put_page(page); + goto repeat; + } get_page(page); spin_unlock(&pagecache_lock); - lock_page(page); - if (!page->buffers || block_flushpage(page, 0)) lru_cache_del(page); @@ -191,11 +196,13 @@ continue; /* partial truncate, clear end of page */ + if (TryLockPage(page)) { + spin_unlock(&pagecache_lock); + goto repeat; + } get_page(page); spin_unlock(&pagecache_lock); - lock_page(page); - memclear_highpage_flush(page, partial, PAGE_CACHE_SIZE-partial); if (page->buffers) block_flushpage(page, partial); @@ -208,6 +215,9 @@ */ UnlockPage(page); page_cache_release(page); + get_page(page); + wait_on_page(page); + put_page(page); goto repeat; } spin_unlock(&pagecache_lock); @@ -233,7 +243,17 @@ page = list_entry(page_lru, struct page, lru); list_del(page_lru); - dispose = &zone->lru_cache; + /* What?! A page is in the LRU queue of another zone?! */ + if (!memclass(page->zone, zone)) + BUG(); + + dispose = &young; + /* the page is in use, we can't free it now */ + if (!page->buffers && page_count(page) > 1) + goto dispose_continue; + + count--; + if (test_and_clear_bit(PG_referenced, &page->flags)) /* Roll the page at the top of the lru list, * we could also be more aggressive putting @@ -243,17 +263,6 @@ goto dispose_continue; dispose = &old; - /* don't account passes over not DMA pages */ - if (zone && (!memclass(page->zone, zone))) - goto dispose_continue; - - count--; - - dispose = &young; - - /* avoid unscalable SMP locking */ - if (!page->buffers && page_count(page) > 1) - goto dispose_continue; if (TryLockPage(page)) goto dispose_continue;
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This archive was generated by hypermail 2b29 : Sun Apr 23 2000 - 21:00:16 EST