[RFC][PATCH 1/2] Swap token re-tuned

[Ashwin Chaugule <ashwin.chaugule@codito.com>]

Try to grab swap token before the VM selects pages for eviction.


Signed-off-by: Ashwin Chaugule <ashwin.chaugule@celunite.com>

-- 

diff --git a/mm/filemap.c b/mm/filemap.c
index afcdc72..190d2c1 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1478,8 +1478,8 @@ no_cached_page:
     * We're only likely to ever get here if MADV_RANDOM is in
     * effect.
     */
+    grab_swap_token(); /* Contend for token _before_ we read-in */
    error = page_cache_read(file, pgoff);
-    grab_swap_token();

    /*
     * The page we want has now been added to the page cache.
diff --git a/mm/memory.c b/mm/memory.c
index 92a3ebd..52eb9b8 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1974,6 +1974,7 @@ static int do_swap_page(struct mm_struct
    delayacct_set_flag(DELAYACCT_PF_SWAPIN);
    page = lookup_swap_cache(entry);
    if (!page) {
+        grab_swap_token(); /* Contend for token _before_ we read-in */
         swapin_readahead(entry, address, vma);
         page = read_swap_cache_async(entry, vma, address);
        if (!page) {
@@ -1991,7 +1992,6 @@ static int do_swap_page(struct mm_struct
        /* Had to read the page from swap area: Major fault */
        ret = VM_FAULT_MAJOR;
        count_vm_event(PGMAJFAULT);
-        grab_swap_token();
    }

    delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
-- 


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