On Thu, May 14, 2015 at 2:17 PM, Vlastimil Babka [off-list ref] wrote:

On 03/27/2015 06:09 PM, Konstantin Khlebnikov wrote:

quoted

On 27.03.2015 19:40, Vlastimil Babka wrote:

quoted

From: Jerome Marchand <redacted>

Currently looking at /proc/<pid>/status or statm, there is no way to
distinguish shmem pages from pages mapped to a regular file (shmem
pages are mapped to /dev/zero), even though their implication in
actual memory use is quite different.
This patch adds MM_SHMEMPAGES counter to mm_rss_stat to account for
shmem pages instead of MM_FILEPAGES.

Signed-off-by: Jerome Marchand <redacted>
Signed-off-by: Vlastimil Babka <redacted>
---

quoted

--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h

@@ -327,9 +327,12 @@ struct core_state {
   };

   enum {
-       MM_FILEPAGES,
-       MM_ANONPAGES,
-       MM_SWAPENTS,
+       MM_FILEPAGES,   /* Resident file mapping pages */
+       MM_ANONPAGES,   /* Resident anonymous pages */
+       MM_SWAPENTS,    /* Anonymous swap entries */
+#ifdef CONFIG_SHMEM
+       MM_SHMEMPAGES,  /* Resident shared memory pages */
+#endif

I prefer to keep that counter unconditionally:
kernel has MM_SWAPENTS even without CONFIG_SWAP.

Hmm, so just for consistency? I don't see much reason to make life harder
for tiny systems, especially when it's not too much effort.

Profit is vague, I guess slab anyway will round size to the next
cacheline or power-of-two.
That conditional (non)existence just adds unneeded code lines.

quoted

quoted

        NR_MM_COUNTERS
   };

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