• Huang Ying's avatar
    memory tiering: rate limit NUMA migration throughput · c6833e10
    Huang Ying authored
    In NUMA balancing memory tiering mode, if there are hot pages in slow
    memory node and cold pages in fast memory node, we need to promote/demote
    hot/cold pages between the fast and cold memory nodes.
    
    A choice is to promote/demote as fast as possible.  But the CPU cycles and
    memory bandwidth consumed by the high promoting/demoting throughput will
    hurt the latency of some workload because of accessing inflating and slow
    memory bandwidth contention.
    
    A way to resolve this issue is to restrict the max promoting/demoting
    throughput.  It will take longer to finish the promoting/demoting.  But
    the workload latency will be better.  This is implemented in this patch as
    the page promotion rate limit mechanism.
    
    The number of the candidate pages to be promoted to the fast memory node
    via NUMA balancing is counted, if the count exceeds the limit specified by
    the users, the NUMA balancing promotion will be stopped until the next
    second.
    
    A new sysctl knob kernel.numa_balancing_promote_rate_limit_MBps is added
    for the users to specify the limit.
    
    Link: https://lkml.kernel.org/r/20220713083954.34196-3-ying.huang@intel.comSigned-off-by: default avatar"Huang, Ying" <ying.huang@intel.com>
    Reviewed-by: default avatarBaolin Wang <baolin.wang@linux.alibaba.com>
    Tested-by: default avatarBaolin Wang <baolin.wang@linux.alibaba.com>
    Cc: Dave Hansen <dave.hansen@linux.intel.com>
    Cc: Johannes Weiner <hannes@cmpxchg.org>
    Cc: Mel Gorman <mgorman@techsingularity.net>
    Cc: Michal Hocko <mhocko@suse.com>
    Cc: osalvador <osalvador@suse.de>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Rik van Riel <riel@surriel.com>
    Cc: Shakeel Butt <shakeelb@google.com>
    Cc: Wei Xu <weixugc@google.com>
    Cc: Yang Shi <shy828301@gmail.com>
    Cc: Zhong Jiang <zhongjiang-ali@linux.alibaba.com>
    Cc: Zi Yan <ziy@nvidia.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    c6833e10
sysctl.c 59.7 KB