[PATCH] generic_file_map drop-behind fix

From: Rik van Riel (riel@conectiva.com.br)
Date: Thu Dec 21 2000 - 16:49:47 EST


Hi Ingo,

the attached patch (against 2.4.0-test12-pre3) should fix the
problem where generic_file_write() causes a page to be moved
to the inactive list when the program is still writing to it.

Does this patch fix the web benching bottleneck in tux2 ? ;)

regards,

Rik

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--- linux-2.4.0-test12-pre3/mm/filemap.c.orig 2000/12/21 18:20:17 +++ linux/mm/filemap.c 2000/12/21 21:31:39 @@ -2436,7 +2436,7 @@ } while (count) { - unsigned long bytes, index, offset; + unsigned long bytes, index, offset, partial = 0; char *kaddr; /* @@ -2446,8 +2446,10 @@ offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */ index = pos >> PAGE_CACHE_SHIFT; bytes = PAGE_CACHE_SIZE - offset; - if (bytes > count) + if (bytes > count) { bytes = count; + partial = 1; + } status = -ENOMEM; /* we'll assign it later anyway */ page = __grab_cache_page(mapping, index, &cached_page); @@ -2478,9 +2480,17 @@ buf += status; } unlock: - /* Mark it unlocked again and drop the page.. */ + /* + * Mark it unlocked again and release the page. + * In order to prevent large (fast) file writes + * from causing too much memory pressure we move + * completely written pages to the inactive list. + * We do, however, try to keep the pages that may + * still be written to (ie. partially written pages). + */ UnlockPage(page); - deactivate_page(page); + if (!partial) + deactivate_page(page); page_cache_release(page); if (status < 0)

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