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Subject[PATCH] generic_file_map drop-behind fix
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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Trailer at 11.

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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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