[v2,08/11] mm/vmstat: switch counter modification to cmpxchg

Message ID	20230209153204.846239718@redhat.com (mailing list archive)
State	New
Headers	show Return-Path: <owner-linux-mm@kvack.org> Message-ID: <20230209153204.846239718@redhat.com> User-Agent: quilt/0.67 Date: Thu, 09 Feb 2023 12:01:58 -0300 From: Marcelo Tosatti <mtosatti@redhat.com> To: Christoph Lameter <cl@linux.com> Cc: Aaron Tomlin <atomlin@atomlin.com>, Frederic Weisbecker <frederic@kernel.org>, Andrew Morton <akpm@linux-foundation.org>, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Marcelo Tosatti <mtosatti@redhat.com> Subject: [PATCH v2 08/11] mm/vmstat: switch counter modification to cmpxchg References: <20230209150150.380060673@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org Precedence: bulk
Series	fold per-CPU vmstats remotely \| expand [v2,00/11] fold per-CPU vmstats remotely [v2,01/11] mm/vmstat: remove remote node draining [v2,02/11] this_cpu_cmpxchg: ARM64: switch this_cpu_cmpxchg to locked, add _local function [v2,03/11] this_cpu_cmpxchg: loongarch: switch this_cpu_cmpxchg to locked, add _local function [v2,04/11] this_cpu_cmpxchg: S390: switch this_cpu_cmpxchg to locked, add _local function [v2,05/11] this_cpu_cmpxchg: x86: switch this_cpu_cmpxchg to locked, add _local function [v2,06/11] this_cpu_cmpxchg: asm-generic: switch this_cpu_cmpxchg to locked, add _local function [v2,07/11] convert this_cpu_cmpxchg users to this_cpu_cmpxchg_local [v2,08/11] mm/vmstat: switch counter modification to cmpxchg [v2,09/11] mm/vmstat: use cmpxchg loop in cpu_vm_stats_fold [v2,10/11] mm/vmstat: switch vmstat shepherd to flush per-CPU counters remotely [v2,11/11] mm/vmstat: refresh stats remotely instead of via work item

Index: linux-vmstat-remote/mm/vmstat.c =================================================================== --- linux-vmstat-remote.orig/mm/vmstat.c +++ linux-vmstat-remote/mm/vmstat.c @@ -334,6 +334,188 @@ void set_pgdat_percpu_threshold(pg_data_ } } +#ifdef CONFIG_HAVE_CMPXCHG_LOCAL +/* + * If we have cmpxchg_local support then we do not need to incur the overhead + * that comes with local_irq_save/restore if we use this_cpu_cmpxchg. + * + * mod_state() modifies the zone counter state through atomic per cpu + * operations. + * + * Overstep mode specifies how overstep should handled: + * 0 No overstepping + * 1 Overstepping half of threshold + * -1 Overstepping minus half of threshold + */ +static inline void mod_zone_state(struct zone *zone, enum zone_stat_item item, + long delta, int overstep_mode) +{ + struct per_cpu_zonestat __percpu *pcp = zone->per_cpu_zonestats; + s8 __percpu *p = pcp->vm_stat_diff + item; + long o, n, t, z; + + do { + z = 0; /* overflow to zone counters */ + + /* + * The fetching of the stat_threshold is racy. We may apply + * a counter threshold to the wrong the cpu if we get + * rescheduled while executing here. However, the next + * counter update will apply the threshold again and + * therefore bring the counter under the threshold again. + * + * Most of the time the thresholds are the same anyways + * for all cpus in a zone. + */ + t = this_cpu_read(pcp->stat_threshold); + + o = this_cpu_read(*p); + n = delta + o; + + if (abs(n) > t) { + int os = overstep_mode * (t >> 1); + + /* Overflow must be added to zone counters */ + z = n + os; + n = -os; + } + } while (this_cpu_cmpxchg(*p, o, n) != o); + + if (z) + zone_page_state_add(z, zone, item); +} + +void mod_zone_page_state(struct zone *zone, enum zone_stat_item item, + long delta) +{ + mod_zone_state(zone, item, delta, 0); +} +EXPORT_SYMBOL(mod_zone_page_state); + +void __mod_zone_page_state(struct zone *zone, enum zone_stat_item item, + long delta) +{ + mod_zone_state(zone, item, delta, 0); +} +EXPORT_SYMBOL(__mod_zone_page_state); + +void inc_zone_page_state(struct page *page, enum zone_stat_item item) +{ + mod_zone_state(page_zone(page), item, 1, 1); +} +EXPORT_SYMBOL(inc_zone_page_state); + +void __inc_zone_page_state(struct page *page, enum zone_stat_item item) +{ + mod_zone_state(page_zone(page), item, 1, 1); +} +EXPORT_SYMBOL(__inc_zone_page_state); + +void dec_zone_page_state(struct page *page, enum zone_stat_item item) +{ + mod_zone_state(page_zone(page), item, -1, -1); +} +EXPORT_SYMBOL(dec_zone_page_state); + +void __dec_zone_page_state(struct page *page, enum zone_stat_item item) +{ + mod_zone_state(page_zone(page), item, -1, -1); +} +EXPORT_SYMBOL(__dec_zone_page_state); + +static inline void mod_node_state(struct pglist_data *pgdat, + enum node_stat_item item, + int delta, int overstep_mode) +{ + struct per_cpu_nodestat __percpu *pcp = pgdat->per_cpu_nodestats; + s8 __percpu *p = pcp->vm_node_stat_diff + item; + long o, n, t, z; + + if (vmstat_item_in_bytes(item)) { + /* + * Only cgroups use subpage accounting right now; at + * the global level, these items still change in + * multiples of whole pages. Store them as pages + * internally to keep the per-cpu counters compact. + */ + VM_WARN_ON_ONCE(delta & (PAGE_SIZE - 1)); + delta >>= PAGE_SHIFT; + } + + do { + z = 0; /* overflow to node counters */ + + /* + * The fetching of the stat_threshold is racy. We may apply + * a counter threshold to the wrong the cpu if we get + * rescheduled while executing here. However, the next + * counter update will apply the threshold again and + * therefore bring the counter under the threshold again. + * + * Most of the time the thresholds are the same anyways + * for all cpus in a node. + */ + t = this_cpu_read(pcp->stat_threshold); + + o = this_cpu_read(*p); + n = delta + o; + + if (abs(n) > t) { + int os = overstep_mode * (t >> 1); + + /* Overflow must be added to node counters */ + z = n + os; + n = -os; + } + } while (this_cpu_cmpxchg(*p, o, n) != o); + + if (z) + node_page_state_add(z, pgdat, item); +} + +void mod_node_page_state(struct pglist_data *pgdat, enum node_stat_item item, + long delta) +{ + mod_node_state(pgdat, item, delta, 0); +} +EXPORT_SYMBOL(mod_node_page_state); + +void __mod_node_page_state(struct pglist_data *pgdat, enum node_stat_item item, + long delta) +{ + mod_node_state(pgdat, item, delta, 0); +} +EXPORT_SYMBOL(__mod_node_page_state); + +void inc_node_state(struct pglist_data *pgdat, enum node_stat_item item) +{ + mod_node_state(pgdat, item, 1, 1); +} + +void inc_node_page_state(struct page *page, enum node_stat_item item) +{ + mod_node_state(page_pgdat(page), item, 1, 1); +} +EXPORT_SYMBOL(inc_node_page_state); + +void __inc_node_page_state(struct page *page, enum node_stat_item item) +{ + mod_node_state(page_pgdat(page), item, 1, 1); +} +EXPORT_SYMBOL(__inc_node_page_state); + +void dec_node_page_state(struct page *page, enum node_stat_item item) +{ + mod_node_state(page_pgdat(page), item, -1, -1); +} +EXPORT_SYMBOL(dec_node_page_state); + +void __dec_node_page_state(struct page *page, enum node_stat_item item) +{ + mod_node_state(page_pgdat(page), item, -1, -1); +} +EXPORT_SYMBOL(__dec_node_page_state); +#else /* * For use when we know that interrupts are disabled, * or when we know that preemption is disabled and that @@ -541,149 +723,6 @@ void __dec_node_page_state(struct page * } EXPORT_SYMBOL(__dec_node_page_state); -#ifdef CONFIG_HAVE_CMPXCHG_LOCAL -/* - * If we have cmpxchg_local support then we do not need to incur the overhead - * that comes with local_irq_save/restore if we use this_cpu_cmpxchg. - * - * mod_state() modifies the zone counter state through atomic per cpu - * operations. - * - * Overstep mode specifies how overstep should handled: - * 0 No overstepping - * 1 Overstepping half of threshold - * -1 Overstepping minus half of threshold -*/ -static inline void mod_zone_state(struct zone *zone, - enum zone_stat_item item, long delta, int overstep_mode) -{ - struct per_cpu_zonestat __percpu *pcp = zone->per_cpu_zonestats; - s8 __percpu *p = pcp->vm_stat_diff + item; - long o, n, t, z; - - do { - z = 0; /* overflow to zone counters */ - - /* - * The fetching of the stat_threshold is racy. We may apply - * a counter threshold to the wrong the cpu if we get - * rescheduled while executing here. However, the next - * counter update will apply the threshold again and - * therefore bring the counter under the threshold again. - * - * Most of the time the thresholds are the same anyways - * for all cpus in a zone. - */ - t = this_cpu_read(pcp->stat_threshold); - - o = this_cpu_read(*p); - n = delta + o; - - if (abs(n) > t) { - int os = overstep_mode * (t >> 1) ; - - /* Overflow must be added to zone counters */ - z = n + os; - n = -os; - } - } while (this_cpu_cmpxchg(*p, o, n) != o); - - if (z) - zone_page_state_add(z, zone, item); -} - -void mod_zone_page_state(struct zone *zone, enum zone_stat_item item, - long delta) -{ - mod_zone_state(zone, item, delta, 0); -} -EXPORT_SYMBOL(mod_zone_page_state); - -void inc_zone_page_state(struct page *page, enum zone_stat_item item) -{ - mod_zone_state(page_zone(page), item, 1, 1); -} -EXPORT_SYMBOL(inc_zone_page_state); - -void dec_zone_page_state(struct page *page, enum zone_stat_item item) -{ - mod_zone_state(page_zone(page), item, -1, -1); -} -EXPORT_SYMBOL(dec_zone_page_state); - -static inline void mod_node_state(struct pglist_data *pgdat, - enum node_stat_item item, int delta, int overstep_mode) -{ - struct per_cpu_nodestat __percpu *pcp = pgdat->per_cpu_nodestats; - s8 __percpu *p = pcp->vm_node_stat_diff + item; - long o, n, t, z; - - if (vmstat_item_in_bytes(item)) { - /* - * Only cgroups use subpage accounting right now; at - * the global level, these items still change in - * multiples of whole pages. Store them as pages - * internally to keep the per-cpu counters compact. - */ - VM_WARN_ON_ONCE(delta & (PAGE_SIZE - 1)); - delta >>= PAGE_SHIFT; - } - - do { - z = 0; /* overflow to node counters */ - - /* - * The fetching of the stat_threshold is racy. We may apply - * a counter threshold to the wrong the cpu if we get - * rescheduled while executing here. However, the next - * counter update will apply the threshold again and - * therefore bring the counter under the threshold again. - * - * Most of the time the thresholds are the same anyways - * for all cpus in a node. - */ - t = this_cpu_read(pcp->stat_threshold); - - o = this_cpu_read(*p); - n = delta + o; - - if (abs(n) > t) { - int os = overstep_mode * (t >> 1) ; - - /* Overflow must be added to node counters */ - z = n + os; - n = -os; - } - } while (this_cpu_cmpxchg(*p, o, n) != o); - - if (z) - node_page_state_add(z, pgdat, item); -} - -void mod_node_page_state(struct pglist_data *pgdat, enum node_stat_item item, - long delta) -{ - mod_node_state(pgdat, item, delta, 0); -} -EXPORT_SYMBOL(mod_node_page_state); - -void inc_node_state(struct pglist_data *pgdat, enum node_stat_item item) -{ - mod_node_state(pgdat, item, 1, 1); -} - -void inc_node_page_state(struct page *page, enum node_stat_item item) -{ - mod_node_state(page_pgdat(page), item, 1, 1); -} -EXPORT_SYMBOL(inc_node_page_state); - -void dec_node_page_state(struct page *page, enum node_stat_item item) -{ - mod_node_state(page_pgdat(page), item, -1, -1); -} -EXPORT_SYMBOL(dec_node_page_state); -#else /* * Use interrupt disable to serialize counter updates */

[v2,08/11] mm/vmstat: switch counter modification to cmpxchg

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