On Fri, Nov 20, 2015 at 01:58:57PM +0300, Vladimir Davydov wrote: > On Thu, Nov 12, 2015 at 06:41:27PM -0500, Johannes Weiner wrote: > > There won't be a tcp control soft limit, so integrating the memcg code > > into the global skmem limiting scheme complicates things > > unnecessarily. Replace this with simple and clear charge and uncharge > > calls--hidden behind a jump label--to account skb memory. > > > > Note that this is not purely aesthetic: as a result of shoehorning the > > per-memcg code into the same memory accounting functions that handle > > the global level, the old code would compare the per-memcg consumption > > against the smaller of the per-memcg limit and the global limit. This > > allowed the total consumption of multiple sockets to exceed the global > > limit, as long as the individual sockets stayed within bounds. After > > this change, the code will always compare the per-memcg consumption to > > the per-memcg limit, and the global consumption to the global limit, > > and thus close this loophole. > > > > Without a soft limit, the per-memcg memory pressure state in sockets > > is generally questionable. However, we did it until now, so we > > continue to enter it when the hard limit is hit, and packets are > > dropped, to let other sockets in the cgroup know that they shouldn't > > grow their transmit windows, either. However, keep it simple in the > > new callback model and leave memory pressure lazily when the next > > packet is accepted (as opposed to doing it synchroneously when packets > > are processed). When packets are dropped, network performance will > > already be in the toilet, so that should be a reasonable trade-off. > > > > As described above, consumption is now checked on the per-memcg level > > and the global level separately. Likewise, memory pressure states are > > maintained on both the per-memcg level and the global level, and a > > socket is considered under pressure when either level asserts as much. > > > > Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx> > > It leaves the legacy functionality intact, while making the code look > much better. > > Reviewed-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx> Thank you very much! -- 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=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>