Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751424AbdIOJYw (ORCPT ); Fri, 15 Sep 2017 05:24:52 -0400 Received: from mga04.intel.com ([192.55.52.120]:3719 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751157AbdIOJYs (ORCPT ); Fri, 15 Sep 2017 05:24:48 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.42,396,1500966000"; d="scan'208";a="152182682" From: Kemi Wang To: "Luis R . Rodriguez" , Kees Cook , Andrew Morton , Jonathan Corbet , Michal Hocko , Mel Gorman , Johannes Weiner , Christopher Lameter , Sebastian Andrzej Siewior , Vlastimil Babka , Hillf Danton Cc: Dave , Tim Chen , Andi Kleen , Jesper Dangaard Brouer , Ying Huang , Aaron Lu , Kemi Wang , Proc sysctl , Linux MM , Linux Kernel Subject: [PATCH 1/3] mm, sysctl: make VM stats configurable Date: Fri, 15 Sep 2017 17:23:24 +0800 Message-Id: <1505467406-9945-2-git-send-email-kemi.wang@intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1505467406-9945-1-git-send-email-kemi.wang@intel.com> References: <1505467406-9945-1-git-send-email-kemi.wang@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4797 Lines: 155 This patch adds a tunable interface that allows VM stats configurable, as suggested by Dave Hansen and Ying Huang. When performance becomes a bottleneck and you can tolerate some possible tool breakage and some decreased counter precision (e.g. numa counter), you can do: echo [C|c]oarse > /proc/sys/vm/vmstat_mode When performance is not a bottleneck and you want all tooling to work, you can do: echo [S|s]trict > /proc/sys/vm/vmstat_mode We recommend automatic detection of virtual memory statistics by system, this is also system default configuration, you can do: echo [A|a]uto > /proc/sys/vm/vmstat_mode The next patch handles numa statistics distinctively based-on different VM stats mode. Reported-by: Jesper Dangaard Brouer Suggested-by: Dave Hansen Suggested-by: Ying Huang Signed-off-by: Kemi Wang --- include/linux/vmstat.h | 14 ++++++++++ kernel/sysctl.c | 7 +++++ mm/vmstat.c | 70 ++++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 91 insertions(+) diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h index ade7cb5..c3634c7 100644 --- a/include/linux/vmstat.h +++ b/include/linux/vmstat.h @@ -9,6 +9,20 @@ extern int sysctl_stat_interval; +/* + * vmstat_mode: + * 0 = auto mode of vmstat, automatic detection of VM statistics. + * 1 = strict mode of vmstat, keep all VM statistics. + * 2 = coarse mode of vmstat, ignore unimportant VM statistics. + */ +#define VMSTAT_AUTO_MODE 0 +#define VMSTAT_STRICT_MODE 1 +#define VMSTAT_COARSE_MODE 2 +#define VMSTAT_MODE_LEN 16 +extern char sysctl_vmstat_mode[]; +extern int sysctl_vmstat_mode_handler(struct ctl_table *table, int write, + void __user *buffer, size_t *length, loff_t *ppos); + #ifdef CONFIG_VM_EVENT_COUNTERS /* * Light weight per cpu counter implementation. diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 6648fbb..f5b813b 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -1234,6 +1234,13 @@ static struct ctl_table kern_table[] = { static struct ctl_table vm_table[] = { { + .procname = "vmstat_mode", + .data = &sysctl_vmstat_mode, + .maxlen = VMSTAT_MODE_LEN, + .mode = 0644, + .proc_handler = sysctl_vmstat_mode_handler, + }, + { .procname = "overcommit_memory", .data = &sysctl_overcommit_memory, .maxlen = sizeof(sysctl_overcommit_memory), diff --git a/mm/vmstat.c b/mm/vmstat.c index 4bb13e7..e675ad2 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -32,6 +32,76 @@ #define NUMA_STATS_THRESHOLD (U16_MAX - 2) +int vmstat_mode = VMSTAT_AUTO_MODE; +char sysctl_vmstat_mode[VMSTAT_MODE_LEN] = "auto"; +static const char *vmstat_mode_name[3] = {"auto", "strict", "coarse"}; +static DEFINE_MUTEX(vmstat_mode_lock); + + +static int __parse_vmstat_mode(char *s) +{ + const char *str = s; + + if (strcmp(str, "auto") == 0 || strcmp(str, "Auto") == 0) + vmstat_mode = VMSTAT_AUTO_MODE; + else if (strcmp(str, "strict") == 0 || strcmp(str, "Strict") == 0) + vmstat_mode = VMSTAT_STRICT_MODE; + else if (strcmp(str, "coarse") == 0 || strcmp(str, "Coarse") == 0) + vmstat_mode = VMSTAT_COARSE_MODE; + else { + pr_warn("Ignoring invalid vmstat_mode value: %s\n", s); + return -EINVAL; + } + return 0; +} + +int sysctl_vmstat_mode_handler(struct ctl_table *table, int write, + void __user *buffer, size_t *length, loff_t *ppos) +{ + char old_string[VMSTAT_MODE_LEN]; + int ret, oldval; + + mutex_lock(&vmstat_mode_lock); + if (write) + strncpy(old_string, (char *)table->data, VMSTAT_MODE_LEN); + ret = proc_dostring(table, write, buffer, length, ppos); + if (ret || !write) { + mutex_unlock(&vmstat_mode_lock); + return ret; + } + + oldval = vmstat_mode; + if (__parse_vmstat_mode((char *)table->data)) { + /* + * invalid sysctl_vmstat_mode value, restore saved string + */ + strncpy((char *)table->data, old_string, VMSTAT_MODE_LEN); + vmstat_mode = oldval; + } else { + /* + * check whether vmstat mode changes or not + */ + if (vmstat_mode == oldval) { + /* no change */ + mutex_unlock(&vmstat_mode_lock); + return 0; + } else if (vmstat_mode == VMSTAT_AUTO_MODE) + pr_info("vmstat mode changes from %s to auto mode\n", + vmstat_mode_name[oldval]); + else if (vmstat_mode == VMSTAT_STRICT_MODE) + pr_info("vmstat mode changes from %s to strict mode\n", + vmstat_mode_name[oldval]); + else if (vmstat_mode == VMSTAT_COARSE_MODE) + pr_info("vmstat mode changes from %s to coarse mode\n", + vmstat_mode_name[oldval]); + else + pr_warn("invalid vmstat_mode:%d\n", vmstat_mode); + } + + mutex_unlock(&vmstat_mode_lock); + return 0; +} + #ifdef CONFIG_VM_EVENT_COUNTERS DEFINE_PER_CPU(struct vm_event_state, vm_event_states) = {{0}}; EXPORT_PER_CPU_SYMBOL(vm_event_states); -- 2.7.4