On 03/03/2018 02:48, Alexey Dokuchaev wrote: > On Tue, Nov 22, 2016 at 06:13:46PM +0000, Alan Cox wrote: >> New Revision: 309017 >> URL: https://svnweb.freebsd.org/changeset/base/309017 >> >> Log: >> Remove PG_CACHED-related fields from struct vmmeter, because they are no >> longer used. More precisely, they are always zero because the code that >> decremented and incremented them no longer exists. >> >> Bump __FreeBSD_version to mark this change. >> >> Reviewed by: kib, markj >> Sponsored by: Dell EMC Isilon >> Differential Revision: https://reviews.freebsd.org/D8583 >> >> Modified: head/sys/cddl/compat/opensolaris/sys/kmem.h >> ... >> -#define freemem (vm_cnt.v_free_count + >> vm_cnt.v_cache_count) >> +#define freemem vm_cnt.v_free_count > This looks correct now. > >> Modified: head/sys/compat/linprocfs/linprocfs.c >> ... >> @@ -176,7 +176,7 @@ linprocfs_domeminfo(PFS_FILL_ARGS) >> * like unstaticizing it just for linprocfs's sake. >> */ >> buffers = 0; >> - cached = vm_cnt.v_cache_count * PAGE_SIZE; >> + cached = vm_cnt.v_inactive_count * PAGE_SIZE; > Some applications that make calculations based on the readings from the > /usr/compat/linux/proc/meminfo are broken after this change, e.g. those > that do things like: > > return (totalMem - (freeMem + buffers + cache)) / totalMem; > > because now free memory includes cached one, and above formula gives > bogus negative result. > > In `sys/compat/linprocfs/linprocfs.c', memfree is calculated as follows: > > memtotal = physmem * PAGE_SIZE; > /* > * The correct thing here would be: > * > memfree = vm_cnt.v_free_count * PAGE_SIZE; > memused = memtotal - memfree; > * > * but it might mislead linux binaries into thinking there > * is very little memory left, so we cheat and tell them that > * all memory that isn't wired down is free. > */ > memused = vm_cnt.v_wire_count * PAGE_SIZE; > memfree = memtotal - memused; > > So, when vm.stats.vm.v_cache_count was yielding some (typically small) > result, using the aforementioned trick made sense (because even when > vm_cnt.v_free_count added to vm.stats.vm.v_cache_count it would still > be rather small). This logic no longer applies after this change. > > On my 12-CURRENT i386 system, /usr/compat/linux/proc/meminfo reports: > > % cat /usr/compat/linux/proc/meminfo | head -4 > MemTotal: 3132504 kB > MemFree: 2925936 kB <<< that's a lot > Buffers: 0 kB > Cached: 2212196 kB <<< that's also a lot > > On an older 4.11-STABLE box (also i386), it reports: > > MemTotal: 521828 kB > MemFree: 383976 kB > MemShared: 7480 kB > Buffers: 0 kB > Cached: 22732 kB (can be added to MemFree and still < MemTotal) > > So either the "cheat" have to go away and vm_cnt.v_free_count used as it > should, or cached memory should not be read from vm_cnt.v_inactive_count > but estimated somehow else. Which approach would be more correct?
The former. _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
