On Mon, Mar 19, 2012 at 1:14 AM, Zhu Yanhai <zhu.yanhai@xxxxxxxxx> wrote:
> 2011/4/19 Ying Han <yinghan@xxxxxxxxxx>:
>> This is the main loop of per-memcg background reclaim which is implemented in
>> function balance_mem_cgroup_pgdat().
>>
>> The function performs a priority loop similar to global reclaim. During each
>> iteration it invokes balance_pgdat_node() for all nodes on the system, which
>> is another new function performs background reclaim per node. After reclaiming
>> each node, it checks mem_cgroup_watermark_ok() and breaks the priority loop if
>> it returns true.
>>
>> changelog v6..v5:
>> 1. add mem_cgroup_zone_reclaimable_pages()
>> 2. fix some comment style.
>>
>> changelog v5..v4:
>> 1. remove duplicate check on nodes_empty()
>> 2. add logic to check if the per-memcg lru is empty on the zone.
>>
>> changelog v4..v3:
>> 1. split the select_victim_node and zone_unreclaimable to a seperate patches
>> 2. remove the logic tries to do zone balancing.
>>
>> changelog v3..v2:
>> 1. change mz->all_unreclaimable to be boolean.
>> 2. define ZONE_RECLAIMABLE_RATE macro shared by zone and per-memcg reclaim.
>> 3. some more clean-up.
>>
>> changelog v2..v1:
>> 1. move the per-memcg per-zone clear_unreclaimable into uncharge stage.
>> 2. shared the kswapd_run/kswapd_stop for per-memcg and global background
>> reclaim.
>> 3. name the per-memcg memcg as "memcg-id" (css->id). And the global kswapd
>> keeps the same name.
>> 4. fix a race on kswapd_stop while the per-memcg-per-zone info could be accessed
>> after freeing.
>> 5. add the fairness in zonelist where memcg remember the last zone reclaimed
>> from.
>>
>> Signed-off-by: Ying Han <yinghan@xxxxxxxxxx>
>> ---
>> include/linux/memcontrol.h | 9 +++
>> mm/memcontrol.c | 18 +++++
>> mm/vmscan.c | 151 ++++++++++++++++++++++++++++++++++++++++++++
>> 3 files changed, 178 insertions(+), 0 deletions(-)
>>
>> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
>> index d4ff7f2..a4747b0 100644
>> --- a/include/linux/memcontrol.h
>> +++ b/include/linux/memcontrol.h
>> @@ -115,6 +115,8 @@ extern void mem_cgroup_end_migration(struct mem_cgroup *mem,
>> */
>> int mem_cgroup_inactive_anon_is_low(struct mem_cgroup *memcg);
>> int mem_cgroup_inactive_file_is_low(struct mem_cgroup *memcg);
>> +unsigned long mem_cgroup_zone_reclaimable_pages(struct mem_cgroup *memcg,
>> + struct zone *zone);
>> unsigned long mem_cgroup_zone_nr_pages(struct mem_cgroup *memcg,
>> struct zone *zone,
>> enum lru_list lru);
>> @@ -311,6 +313,13 @@ mem_cgroup_inactive_file_is_low(struct mem_cgroup *memcg)
>> }
>>
>> static inline unsigned long
>> +mem_cgroup_zone_reclaimable_pages(struct mem_cgroup *memcg,
>> + struct zone *zone)
>> +{
>> + return 0;
>> +}
>> +
>> +static inline unsigned long
>> mem_cgroup_zone_nr_pages(struct mem_cgroup *memcg, struct zone *zone,
>> enum lru_list lru)
>> {
>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
>> index 06fddd2..7490147 100644
>> --- a/mm/memcontrol.c
>> +++ b/mm/memcontrol.c
>> @@ -1097,6 +1097,24 @@ int mem_cgroup_inactive_file_is_low(struct mem_cgroup *memcg)
>> return (active > inactive);
>> }
>>
>> +unsigned long mem_cgroup_zone_reclaimable_pages(struct mem_cgroup *memcg,
>> + struct zone *zone)
>> +{
>> + int nr;
>> + int nid = zone_to_nid(zone);
>> + int zid = zone_idx(zone);
>> + struct mem_cgroup_per_zone *mz = mem_cgroup_zoneinfo(memcg, nid, zid);
>> +
>> + nr = MEM_CGROUP_ZSTAT(mz, NR_ACTIVE_FILE) +
>> + MEM_CGROUP_ZSTAT(mz, NR_INACTIVE_FILE);
>> +
>> + if (nr_swap_pages > 0)
>
> Do we also need to check memcg->memsw_is_minimum here? That's to say,
> if (nr_swap_pages > 0 && !memcg->memsw_is_minimum)
> .....
That sounds about right. By given that swapon isn't common in our test
environment, I am not surprised to miss that condition by that time.
--Ying
> --
> Thanks,
> Zhu Yanhai
>
>> + nr += MEM_CGROUP_ZSTAT(mz, NR_ACTIVE_ANON) +
>> + MEM_CGROUP_ZSTAT(mz, NR_INACTIVE_ANON);
>> +
>> + return nr;
>> +}
>> +
>> unsigned long mem_cgroup_zone_nr_pages(struct mem_cgroup *memcg,
>> struct zone *zone,
>> enum lru_list lru)
>> diff --git a/mm/vmscan.c b/mm/vmscan.c
>> index 0060d1e..2a5c734 100644
>> --- a/mm/vmscan.c
>> +++ b/mm/vmscan.c
>> @@ -47,6 +47,8 @@
>>
>> #include <linux/swapops.h>
>>
>> +#include <linux/res_counter.h>
>> +
>> #include "internal.h"
>>
>> #define CREATE_TRACE_POINTS
>> @@ -111,6 +113,8 @@ struct scan_control {
>> * are scanned.
>> */
>> nodemask_t *nodemask;
>> +
>> + int priority;
>> };
>>
>> #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
>> @@ -2625,11 +2629,158 @@ out:
>> finish_wait(wait_h, &wait);
>> }
>>
>> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR
>> +/*
>> + * The function is used for per-memcg LRU. It scanns all the zones of the
>> + * node and returns the nr_scanned and nr_reclaimed.
>> + */
>> +static void balance_pgdat_node(pg_data_t *pgdat, int order,
>> + struct scan_control *sc)
>> +{
>> + int i;
>> + unsigned long total_scanned = 0;
>> + struct mem_cgroup *mem_cont = sc->mem_cgroup;
>> + int priority = sc->priority;
>> +
>> + /*
>> + * This dma->highmem order is consistant with global reclaim.
>> + * We do this because the page allocator works in the opposite
>> + * direction although memcg user pages are mostly allocated at
>> + * highmem.
>> + */
>> + for (i = 0; i < pgdat->nr_zones; i++) {
>> + struct zone *zone = pgdat->node_zones + i;
>> + unsigned long scan = 0;
>> +
>> + scan = mem_cgroup_zone_reclaimable_pages(mem_cont, zone);
>> + if (!scan)
>> + continue;
>> +
>> + sc->nr_scanned = 0;
>> + shrink_zone(priority, zone, sc);
>> + total_scanned += sc->nr_scanned;
>> +
>> + /*
>> + * If we've done a decent amount of scanning and
>> + * the reclaim ratio is low, start doing writepage
>> + * even in laptop mode
>> + */
>> + if (total_scanned > SWAP_CLUSTER_MAX * 2 &&
>> + total_scanned > sc->nr_reclaimed + sc->nr_reclaimed / 2) {
>> + sc->may_writepage = 1;
>> + }
>> + }
>> +
>> + sc->nr_scanned = total_scanned;
>> +}
>> +
>> +/*
>> + * Per cgroup background reclaim.
>> + * TODO: Take off the order since memcg always do order 0
>> + */
>> +static unsigned long balance_mem_cgroup_pgdat(struct mem_cgroup *mem_cont,
>> + int order)
>> +{
>> + int i, nid;
>> + int start_node;
>> + int priority;
>> + bool wmark_ok;
>> + int loop;
>> + pg_data_t *pgdat;
>> + nodemask_t do_nodes;
>> + unsigned long total_scanned;
>> + struct scan_control sc = {
>> + .gfp_mask = GFP_KERNEL,
>> + .may_unmap = 1,
>> + .may_swap = 1,
>> + .nr_to_reclaim = SWAP_CLUSTER_MAX,
>> + .swappiness = vm_swappiness,
>> + .order = order,
>> + .mem_cgroup = mem_cont,
>> + };
>> +
>> +loop_again:
>> + do_nodes = NODE_MASK_NONE;
>> + sc.may_writepage = !laptop_mode;
>> + sc.nr_reclaimed = 0;
>> + total_scanned = 0;
>> +
>> + for (priority = DEF_PRIORITY; priority >= 0; priority--) {
>> + sc.priority = priority;
>> + wmark_ok = false;
>> + loop = 0;
>> +
>> + /* The swap token gets in the way of swapout... */
>> + if (!priority)
>> + disable_swap_token();
>> +
>> + if (priority == DEF_PRIORITY)
>> + do_nodes = node_states[N_ONLINE];
>> +
>> + while (1) {
>> + nid = mem_cgroup_select_victim_node(mem_cont,
>> + &do_nodes);
>> +
>> + /*
>> + * Indicate we have cycled the nodelist once
>> + * TODO: we might add MAX_RECLAIM_LOOP for preventing
>> + * kswapd burning cpu cycles.
>> + */
>> + if (loop == 0) {
>> + start_node = nid;
>> + loop++;
>> + } else if (nid == start_node)
>> + break;
>> +
>> + pgdat = NODE_DATA(nid);
>> + balance_pgdat_node(pgdat, order, &sc);
>> + total_scanned += sc.nr_scanned;
>> +
>> + for (i = pgdat->nr_zones - 1; i >= 0; i--) {
>> + struct zone *zone = pgdat->node_zones + i;
>> +
>> + if (!populated_zone(zone))
>> + continue;
>> + }
>> + if (i < 0)
>> + node_clear(nid, do_nodes);
>> +
>> + if (mem_cgroup_watermark_ok(mem_cont,
>> + CHARGE_WMARK_HIGH)) {
>> + wmark_ok = true;
>> + goto out;
>> + }
>> +
>> + if (nodes_empty(do_nodes)) {
>> + wmark_ok = true;
>> + goto out;
>> + }
>> + }
>> +
>> + if (total_scanned && priority < DEF_PRIORITY - 2)
>> + congestion_wait(WRITE, HZ/10);
>> +
>> + if (sc.nr_reclaimed >= SWAP_CLUSTER_MAX)
>> + break;
>> + }
>> +out:
>> + if (!wmark_ok) {
>> + cond_resched();
>> +
>> + try_to_freeze();
>> +
>> + goto loop_again;
>> + }
>> +
>> + return sc.nr_reclaimed;
>> +}
>> +#else
>> static unsigned long balance_mem_cgroup_pgdat(struct mem_cgroup *mem_cont,
>> int order)
>> {
>> return 0;
>> }
>> +#endif
>>
>> /*
>> * The background pageout daemon, started as a kernel thread
>> --
>> 1.7.3.1
>>
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