> -----Original Message----- > From: Rafael Aquini [mailto:aquini@xxxxxxxxxx] > Sent: Wednesday, June 25, 2014 4:16 PM > To: Motohiro Kosaki > Cc: linux-mm@xxxxxxxxx; Andrew Morton; Rik van Riel; Mel Gorman; Johannes Weiner; Motohiro Kosaki JP; linux- > kernel@xxxxxxxxxxxxxxx > Subject: Re: [PATCH] mm: export NR_SHMEM via sysinfo(2) / si_meminfo() interfaces > > On Wed, Jun 25, 2014 at 12:41:17PM -0700, Motohiro Kosaki wrote: > > > > > > > -----Original Message----- > > > From: Rafael Aquini [mailto:aquini@xxxxxxxxxx] > > > Sent: Wednesday, June 25, 2014 2:40 PM > > > To: linux-mm@xxxxxxxxx > > > Cc: Andrew Morton; Rik van Riel; Mel Gorman; Johannes Weiner; > > > Motohiro Kosaki JP; linux-kernel@xxxxxxxxxxxxxxx > > > Subject: [PATCH] mm: export NR_SHMEM via sysinfo(2) / si_meminfo() > > > interfaces > > > > > > This patch leverages the addition of explicit accounting for pages > > > used by shmem/tmpfs -- "4b02108 mm: oom analysis: add shmem vmstat" > > > -- in order to make the users of sysinfo(2) and si_meminfo*() friends aware of that vmstat entry consistently across the interfaces. > > > > Why? > > Because we do not report consistently across the interfaces we declare exporting that data. Check sysinfo(2) manpage, for instance: > [...] > struct sysinfo { > long uptime; /* Seconds since boot */ > unsigned long loads[3]; /* 1, 5, and 15 minute load averages */ > unsigned long totalram; /* Total usable main memory size */ > unsigned long freeram; /* Available memory size */ > unsigned long sharedram; /* Amount of shared memory */ <<<<< [...] > > userspace tools resorting to sysinfo() syscall will get a hardcoded 0 for shared memory which is reported differently from > /proc/meminfo. > > Also, si_meminfo() & si_meminfo_node() are utilized within the kernel to gather statistics for /proc/meminfo & friends, and so we > can leverage collecting sharedmem from those calls as well, just as we do for totalram, freeram & bufferram. But "Amount of shared memory" didn't mean amout of shmem. It actually meant amout of page of page-count>=2. Again, there is a possibility to change the semantics. But I don't have enough userland knowledge to do. Please investigate and explain why your change don't break any userland. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href