Re: [PATCH v4] mm/memcg: try harder to decrease [memory,memsw].limit_in_bytes
From: Michal Hocko <mhocko@kernel.org>
Date: 2018-01-11 12:46:33
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linux-mm, lkml
On Thu 11-01-18 15:21:33, Andrey Ryabinin wrote:
On 01/11/2018 01:42 PM, Michal Hocko wrote:quoted
On Wed 10-01-18 15:43:17, Andrey Ryabinin wrote: [...]quoted
@@ -2506,15 +2480,13 @@ static int mem_cgroup_resize_limit(struct mem_cgroup *memcg, if (!ret) break; - try_to_free_mem_cgroup_pages(memcg, 1, GFP_KERNEL, !memsw); - - curusage = page_counter_read(counter); - /* Usage is reduced ? */ - if (curusage >= oldusage) - retry_count--; - else - oldusage = curusage; - } while (retry_count); + usage = page_counter_read(counter); + if (!try_to_free_mem_cgroup_pages(memcg, usage - limit, + GFP_KERNEL, !memsw)) {If the usage drops below limit in the meantime then you get underflow and reclaim the whole memcg. I do not think this is a good idea. This can also lead to over reclaim. Why don't you simply stick with the original SWAP_CLUSTER_MAX (aka 1 for try_to_free_mem_cgroup_pages)?Because, if new limit is gigabytes bellow the current usage, retrying to set new limit after reclaiming only 32 pages seems unreasonable.
Who would do insanity like that?
quoted hunk ↗ jump to hunk
@@ -2487,8 +2487,8 @@ static int mem_cgroup_resize_limit(struct mem_cgroup *memcg, if (!ret) break; - usage = page_counter_read(counter); - if (!try_to_free_mem_cgroup_pages(memcg, usage - limit, + nr_pages = max_t(long, 1, page_counter_read(counter) - limit); + if (!try_to_free_mem_cgroup_pages(memcg, nr_pages, GFP_KERNEL, !memsw)) { ret = -EBUSY; break;
How does this address the over reclaim concern? -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>