On Thu, 21 Jul 2022, Yosry Ahmed wrote: > memory.reclaim is a cgroup v2 interface that allows users to > proactively reclaim memory from a memcg, without real memory pressure. > Reclaim operations invoke vmpressure, which is used: > (a) To notify userspace of reclaim efficiency in cgroup v1, and > (b) As a signal for a memcg being under memory pressure for networking > (see mem_cgroup_under_socket_pressure()). > > For (a), vmpressure notifications in v1 are not affected by this change > since memory.reclaim is a v2 feature. > > For (b), the effects of the vmpressure signal (according to Shakeel [1]) > are as follows: > 1. Reducing send and receive buffers of the current socket. > 2. May drop packets on the rx path. > 3. May throttle current thread on the tx path. > > Since proactive reclaim is invoked directly by userspace, not by > memory pressure, it makes sense not to throttle networking. Hence, > this change makes sure that proactive reclaim caused by memory.reclaim > does not trigger vmpressure. > > [1] https://lore.kernel.org/lkml/CALvZod68WdrXEmBpOkadhB5GPYmCXaDZzXH=yyGOCAjFRn4NDQ@xxxxxxxxxxxxxx/ > > Signed-off-by: Yosry Ahmed <yosryahmed@xxxxxxxxxx> Acked-by: David Rientjes <rientjes@xxxxxxxxxx>
