On Fri, 20 Nov 2015 13:37:07 -0500 Johannes Weiner <[email protected]> wrote:
> On Fri, Nov 20, 2015 at 08:02:56PM +0300, Vladimir Davydov wrote: > > We assume there is enough inactive page cache if the size of inactive > > file lru is greater than the size of active file lru, in which case we > > force-scan file lru ignoring anonymous pages. While this logic works > > fine when there are plenty of page cache pages, it fails if the size of > > file lru is small (several MB): in this case (lru_size >> prio) will be > > 0 for normal scan priorities, as a result, if inactive file lru happens > > to be larger than active file lru, anonymous pages of a cgroup will > > never get evicted unless the system experiences severe memory pressure, > > even if there are gigabytes of unused anonymous memory there, which is > > unfair in respect to other cgroups, whose workloads might be page cache > > oriented. > > > > This patch attempts to fix this by elaborating the "enough inactive page > > cache" check: it makes it not only check that inactive lru size > active > > lru size, but also that we will scan something from the cgroup at the > > current scan priority. If these conditions do not hold, we proceed to > > SCAN_FRACT as usual. > > > > Signed-off-by: Vladimir Davydov <[email protected]> > > This makes sense, the inactive:active ratio of the file list alone > does not give the full picture to decide whether to skip anonymous. > > Acked-by: Johannes Weiner <[email protected]> > > > @@ -2046,7 +2046,8 @@ static void get_scan_count(struct lruvec *lruvec, int > > swappiness, > > * There is enough inactive page cache, do not reclaim > > * anything from the anonymous working set right now. > > */ > > - if (!inactive_file_is_low(lruvec)) { > > + if (!inactive_file_is_low(lruvec) && > > + get_lru_size(lruvec, LRU_INACTIVE_FILE) >> sc->priority > 0) { > > The > 0 seems unnecessary, no? There are too many > in this line :-) And an update to the code comment would be helpful. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
