On Mon 30-11-15 15:00:22, Johannes Weiner wrote: > The MemAvailable item in /proc/meminfo is to give users a hint of how > much memory is allocatable without causing swapping, so it excludes > the zones' low watermarks as unavailable to userspace. > > However, for a userspace allocation, kswapd will actually reclaim > until the free pages hit a combination of the high watermark and the > page allocator's lowmem protection that keeps a certain amount of DMA > and DMA32 memory from userspace as well. > > Subtract the full amount we know to be unavailable to userspace from > the number of free pages when calculating MemAvailable.
I am not sure this will make a big or even noticeable difference in the real life but it makes sense. > > Signed-off-by: Johannes Weiner <han...@cmpxchg.org> Acked-by: Michal Hocko <mho...@suse.com> > --- > fs/proc/meminfo.c | 5 +---- > 1 file changed, 1 insertion(+), 4 deletions(-) > > diff --git a/fs/proc/meminfo.c b/fs/proc/meminfo.c > index 9155a5a..df4661a 100644 > --- a/fs/proc/meminfo.c > +++ b/fs/proc/meminfo.c > @@ -57,11 +57,8 @@ static int meminfo_proc_show(struct seq_file *m, void *v) > /* > * Estimate the amount of memory available for userspace allocations, > * without causing swapping. > - * > - * Free memory cannot be taken below the low watermark, before the > - * system starts swapping. > */ > - available = i.freeram - wmark_low; > + available = i.freeram - totalreserve_pages; > > /* > * Not all the page cache can be freed, otherwise the system will > -- > 2.6.2 > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majord...@kvack.org. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: <a href=mailto:"d...@kvack.org";> em...@kvack.org </a> -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
