On Fri, 12 Jul 2013, naveen yadav wrote:

Hi All

I am working on tmpfs. During code analysis I found shmem driver register itself as tmpfs .

cat /proc/meminfo Shmem field read NR_SHMEM enum filed and shows used memory in tmpfs

[root@localhost linux-3.8.2]# cat /proc/meminfo | grep -r Shmem Shmem: 704 kB [root@localhost linux-3.8.2]#

include/linux/mmzone.h enum zone_stat_item { -----cut here------- NR_SHMEM, /* shmem pages (included tmpfs/GEM pages -----cut here }

I have the following query 1-> cat /proc/meminfo | grep -r Shmem show only the used tmpfs memory or it show used tmpfs memory + mata data also (because I found Shmem is bit larger then tempfs used memory )

"Shmem" includes only data, not metadata, nor memory currently swapped out. But it includes tmpfs memory, SysV shared memory (from ipc/shm.c), POSIX shared memory (under /dev/shm), and shared anonymous mappings (from mmap of /dev/zero with MAP_SHARED: see call to shmem_zero_setup() from drivers/char/mem.c): whatever allocates pages through mm/shmem.c.

2-> as per the developer comments NR_SHMEM included tmpfs and GEM pages whct is Gem pages

Ah yes, and the Graphics Execution Manager uses shmem for objects shared with the GPU: see use of shmem_read_mapping_page*() in drivers/gpu/drm/.

3-> is my above code analysis is correct?

I think so. Hugh