From patchwork Wed Nov 18 18:59:08 2009 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Robert Jennings X-Patchwork-Id: 38783 Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from bilbo.ozlabs.org (localhost [127.0.0.1]) by ozlabs.org (Postfix) with ESMTP id 0FBAF100A28 for ; Thu, 19 Nov 2009 05:59:45 +1100 (EST) Received: by ozlabs.org (Postfix) id 0EDBD1007D4; Thu, 19 Nov 2009 05:59:34 +1100 (EST) Delivered-To: linuxppc-dev@ozlabs.org Received: from e34.co.us.ibm.com (e34.co.us.ibm.com [32.97.110.152]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e34.co.us.ibm.com", Issuer "Equifax" (verified OK)) by ozlabs.org (Postfix) with ESMTPS id 43B671007D3 for ; Thu, 19 Nov 2009 05:59:33 +1100 (EST) Received: from d03relay04.boulder.ibm.com (d03relay04.boulder.ibm.com [9.17.195.106]) by e34.co.us.ibm.com (8.14.3/8.13.1) with ESMTP id nAIIsGos030327 for ; Wed, 18 Nov 2009 11:54:16 -0700 Received: from d03av02.boulder.ibm.com (d03av02.boulder.ibm.com [9.17.195.168]) by d03relay04.boulder.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id nAIIxCcq076832 for ; Wed, 18 Nov 2009 11:59:13 -0700 Received: from d03av02.boulder.ibm.com (loopback [127.0.0.1]) by d03av02.boulder.ibm.com (8.14.3/8.13.1/NCO v10.0 AVout) with ESMTP id nAIBqdan011472 for ; Wed, 18 Nov 2009 04:52:40 -0700 Received: from toy.austin.ibm.com (toy.austin.ibm.com [9.53.41.214]) by d03av02.boulder.ibm.com (8.14.3/8.13.1/NCO v10.0 AVin) with ESMTP id nAIBqcUT011462; Wed, 18 Nov 2009 04:52:38 -0700 Received: by toy.austin.ibm.com (Postfix, from userid 1000) id 52A43CCA063; Wed, 18 Nov 2009 12:59:08 -0600 (CST) Date: Wed, 18 Nov 2009 12:59:08 -0600 From: Robert Jennings To: akpm@linux-foundation.org Subject: Re: [patch 3/3] [v2] powerpc: make the CMM memory hotplug aware Message-ID: <20091118185907.GA30950@austin.ibm.com> Mail-Followup-To: akpm@linux-foundation.org, benh@kernel.crashing.org, linuxppc-dev@ozlabs.org, brking@linux.vnet.ibm.com, geralds@linux.vnet.ibm.com, kamezawa.hiroyu@jp.fujitsu.com, mel@csn.ul.ie, mingo@elte.hu, paulus@samba.org, schwidefsky@de.ibm.com References: <200911172240.nAHMeHgE021202@imap1.linux-foundation.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <200911172240.nAHMeHgE021202@imap1.linux-foundation.org> User-Agent: Mutt/1.5.17+20080114 (2008-01-14) Cc: mel@csn.ul.ie, geralds@linux.vnet.ibm.com, linuxppc-dev@ozlabs.org, paulus@samba.org, brking@linux.vnet.ibm.com, mingo@elte.hu, schwidefsky@de.ibm.com, kamezawa.hiroyu@jp.fujitsu.com X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org The Collaborative Memory Manager (CMM) module allocates individual pages over time that are not migratable. On a long running system this can severely impact the ability to find enough pages to support a hotplug memory remove operation. This patch adds a memory isolation notifier and a memory hotplug notifier. The memory isolation notifier will return the number of pages found in the range specified. This is used to determine if all of the used pages in a pageblock are owned by the balloon (or other entities in the notifier chain). The hotplug notifier will free pages in the range which is to be removed. The priority of this hotplug notifier is low so that it will be called near last, this helps avoids removing loaned pages in operations that fail due to other handlers. CMM activity will be halted when hotplug remove operations are active and resume activity after a delay period to allow the hypervisor time to adjust. Signed-off-by: Robert Jennings Cc: Mel Gorman Cc: Ingo Molnar Cc: Brian King Cc: Paul Mackerras Cc: Martin Schwidefsky Cc: Gerald Schaefer Cc: KAMEZAWA Hiroyuki Cc: Benjamin Herrenschmidt Cc: Andrew Morton --- The pages used to track loaned pages should not be marked as MOVABLE, so they need to be handled during a memory offline event. Changes: * The structures for recording loaned pages are not allocated as MOVABLE * The structures for recording loaned pages are removed from sections being taken offline by moving their contents to a newly allocated page. arch/powerpc/platforms/pseries/cmm.c | 254 ++++++++++++++++++++++++++++++++++- 1 file changed, 248 insertions(+), 6 deletions(-) Index: b/arch/powerpc/platforms/pseries/cmm.c =================================================================== --- a/arch/powerpc/platforms/pseries/cmm.c +++ b/arch/powerpc/platforms/pseries/cmm.c @@ -38,19 +38,28 @@ #include #include #include +#include #include "plpar_wrappers.h" #define CMM_DRIVER_VERSION "1.0.0" #define CMM_DEFAULT_DELAY 1 +#define CMM_HOTPLUG_DELAY 5 #define CMM_DEBUG 0 #define CMM_DISABLE 0 #define CMM_OOM_KB 1024 #define CMM_MIN_MEM_MB 256 #define KB2PAGES(_p) ((_p)>>(PAGE_SHIFT-10)) #define PAGES2KB(_p) ((_p)<<(PAGE_SHIFT-10)) +/* + * The priority level tries to ensure that this notifier is called as + * late as possible to reduce thrashing in the shared memory pool. + */ +#define CMM_MEM_HOTPLUG_PRI 1 +#define CMM_MEM_ISOLATE_PRI 15 static unsigned int delay = CMM_DEFAULT_DELAY; +static unsigned int hotplug_delay = CMM_HOTPLUG_DELAY; static unsigned int oom_kb = CMM_OOM_KB; static unsigned int cmm_debug = CMM_DEBUG; static unsigned int cmm_disabled = CMM_DISABLE; @@ -65,6 +74,10 @@ MODULE_VERSION(CMM_DRIVER_VERSION); module_param_named(delay, delay, uint, S_IRUGO | S_IWUSR); MODULE_PARM_DESC(delay, "Delay (in seconds) between polls to query hypervisor paging requests. " "[Default=" __stringify(CMM_DEFAULT_DELAY) "]"); +module_param_named(hotplug_delay, hotplug_delay, uint, S_IRUGO | S_IWUSR); +MODULE_PARM_DESC(delay, "Delay (in seconds) after memory hotplug remove " + "before loaning resumes. " + "[Default=" __stringify(CMM_HOTPLUG_DELAY) "]"); module_param_named(oom_kb, oom_kb, uint, S_IRUGO | S_IWUSR); MODULE_PARM_DESC(oom_kb, "Amount of memory in kb to free on OOM. " "[Default=" __stringify(CMM_OOM_KB) "]"); @@ -92,6 +105,9 @@ static unsigned long oom_freed_pages; static struct cmm_page_array *cmm_page_list; static DEFINE_SPINLOCK(cmm_lock); +static DEFINE_MUTEX(hotplug_mutex); +static int hotplug_occurred; /* protected by the hotplug mutex */ + static struct task_struct *cmm_thread_ptr; /** @@ -110,6 +126,17 @@ static long cmm_alloc_pages(long nr) cmm_dbg("Begin request for %ld pages\n", nr); while (nr) { + /* Exit if a hotplug operation is in progress or occurred */ + if (mutex_trylock(&hotplug_mutex)) { + if (hotplug_occurred) { + mutex_unlock(&hotplug_mutex); + break; + } + mutex_unlock(&hotplug_mutex); + } else { + break; + } + addr = __get_free_page(GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY | __GFP_NOMEMALLOC); if (!addr) @@ -119,8 +146,9 @@ static long cmm_alloc_pages(long nr) if (!pa || pa->index >= CMM_NR_PAGES) { /* Need a new page for the page list. */ spin_unlock(&cmm_lock); - npa = (struct cmm_page_array *)__get_free_page(GFP_NOIO | __GFP_NOWARN | - __GFP_NORETRY | __GFP_NOMEMALLOC); + npa = (struct cmm_page_array *)__get_free_page( + GFP_NOIO | __GFP_NOWARN | + __GFP_NORETRY | __GFP_NOMEMALLOC); if (!npa) { pr_info("%s: Can not allocate new page list\n", __func__); free_page(addr); @@ -273,9 +301,28 @@ static int cmm_thread(void *dummy) while (1) { timeleft = msleep_interruptible(delay * 1000); - if (kthread_should_stop() || timeleft) { - loaned_pages_target = loaned_pages; + if (kthread_should_stop() || timeleft) break; + + if (mutex_trylock(&hotplug_mutex)) { + if (hotplug_occurred) { + hotplug_occurred = 0; + mutex_unlock(&hotplug_mutex); + cmm_dbg("Hotplug operation has occurred, " + "loaning activity suspended " + "for %d seconds.\n", + hotplug_delay); + timeleft = msleep_interruptible(hotplug_delay * + 1000); + if (kthread_should_stop() || timeleft) + break; + continue; + } + mutex_unlock(&hotplug_mutex); + } else { + cmm_dbg("Hotplug operation in progress, activity " + "suspended\n"); + continue; } cmm_get_mpp(); @@ -405,6 +452,193 @@ static struct notifier_block cmm_reboot_ }; /** + * cmm_count_pages - Count the number of pages loaned in a particular range. + * + * @arg: memory_isolate_notify structure with address range and count + * + * Return value: + * 0 on success + **/ +static unsigned long cmm_count_pages(void *arg) +{ + struct memory_isolate_notify *marg = arg; + struct cmm_page_array *pa; + unsigned long start = (unsigned long)pfn_to_kaddr(marg->start_pfn); + unsigned long end = start + (marg->nr_pages << PAGE_SHIFT); + unsigned long idx; + + spin_lock(&cmm_lock); + pa = cmm_page_list; + while (pa) { + if ((unsigned long)pa >= start && (unsigned long)pa < end) + marg->pages_found++; + for (idx = 0; idx < pa->index; idx++) + if (pa->page[idx] >= start && pa->page[idx] < end) + marg->pages_found++; + pa = pa->next; + } + spin_unlock(&cmm_lock); + return 0; +} + +/** + * cmm_memory_isolate_cb - Handle memory isolation notifier calls + * @self: notifier block struct + * @action: action to take + * @arg: struct memory_isolate_notify data for handler + * + * Return value: + * NOTIFY_OK or notifier error based on subfunction return value + **/ +static int cmm_memory_isolate_cb(struct notifier_block *self, + unsigned long action, void *arg) +{ + int ret = 0; + + if (action == MEM_ISOLATE_COUNT) + ret = cmm_count_pages(arg); + + if (ret) + ret = notifier_from_errno(ret); + else + ret = NOTIFY_OK; + + return ret; +} + +static struct notifier_block cmm_mem_isolate_nb = { + .notifier_call = cmm_memory_isolate_cb, + .priority = CMM_MEM_ISOLATE_PRI +}; + +/** + * cmm_mem_going_offline - Unloan pages where memory is to be removed + * @arg: memory_notify structure with page range to be offlined + * + * Return value: + * 0 on success + **/ +static int cmm_mem_going_offline(void *arg) +{ + struct memory_notify *marg = arg; + unsigned long start_page = (unsigned long)pfn_to_kaddr(marg->start_pfn); + unsigned long end_page = start_page + (marg->nr_pages << PAGE_SHIFT); + struct cmm_page_array *pa_curr, *pa_last, *npa; + unsigned long idx; + unsigned long freed = 0; + + cmm_dbg("Memory going offline, searching 0x%lx (%ld pages).\n", + start_page, marg->nr_pages); + spin_lock(&cmm_lock); + + /* Search the page list for pages in the range to be offlined */ + pa_last = pa_curr = cmm_page_list; + while (pa_curr) { + for (idx = (pa_curr->index - 1); (idx + 1) > 0; idx--) { + if ((pa_curr->page[idx] < start_page) || + (pa_curr->page[idx] >= end_page)) + continue; + + plpar_page_set_active(__pa(pa_curr->page[idx])); + free_page(pa_curr->page[idx]); + freed++; + loaned_pages--; + totalram_pages++; + pa_curr->page[idx] = pa_last->page[--pa_last->index]; + if (pa_last->index == 0) { + if (pa_curr == pa_last) + pa_curr = pa_last->next; + pa_last = pa_last->next; + free_page((unsigned long)cmm_page_list); + cmm_page_list = pa_last; + continue; + } + } + pa_curr = pa_curr->next; + } + + /* Search for page list structures in the range to be offlined */ + pa_last = NULL; + pa_curr = cmm_page_list; + while (pa_curr) { + if (((unsigned long)pa_curr >= start_page) && + ((unsigned long)pa_curr < end_page)) { + npa = (struct cmm_page_array *)__get_free_page( + GFP_NOIO | __GFP_NOWARN | + __GFP_NORETRY | __GFP_NOMEMALLOC); + if (!npa) { + spin_unlock(&cmm_lock); + cmm_dbg("Failed to allocate memory for list " + "management. Memory hotplug " + "failed.\n"); + return ENOMEM; + } + memcpy(npa, pa_curr, PAGE_SIZE); + if (pa_curr == cmm_page_list) + cmm_page_list = npa; + if (pa_last) + pa_last->next = npa; + free_page((unsigned long) pa_curr); + freed++; + pa_curr = npa; + } + + pa_last = pa_curr; + pa_curr = pa_curr->next; + } + + spin_unlock(&cmm_lock); + cmm_dbg("Released %ld pages in the search range.\n", freed); + + return 0; +} + +/** + * cmm_memory_cb - Handle memory hotplug notifier calls + * @self: notifier block struct + * @action: action to take + * @arg: struct memory_notify data for handler + * + * Return value: + * NOTIFY_OK or notifier error based on subfunction return value + * + **/ +static int cmm_memory_cb(struct notifier_block *self, + unsigned long action, void *arg) +{ + int ret = 0; + + switch (action) { + case MEM_GOING_OFFLINE: + mutex_lock(&hotplug_mutex); + hotplug_occurred = 1; + ret = cmm_mem_going_offline(arg); + break; + case MEM_OFFLINE: + case MEM_CANCEL_OFFLINE: + mutex_unlock(&hotplug_mutex); + cmm_dbg("Memory offline operation complete.\n"); + break; + case MEM_GOING_ONLINE: + case MEM_ONLINE: + case MEM_CANCEL_ONLINE: + break; + } + + if (ret) + ret = notifier_from_errno(ret); + else + ret = NOTIFY_OK; + + return ret; +} + +static struct notifier_block cmm_mem_nb = { + .notifier_call = cmm_memory_cb, + .priority = CMM_MEM_HOTPLUG_PRI +}; + +/** * cmm_init - Module initialization * * Return value: @@ -426,18 +660,24 @@ static int cmm_init(void) if ((rc = cmm_sysfs_register(&cmm_sysdev))) goto out_reboot_notifier; + if (register_memory_notifier(&cmm_mem_nb) || + register_memory_isolate_notifier(&cmm_mem_isolate_nb)) + goto out_unregister_notifier; + if (cmm_disabled) return rc; cmm_thread_ptr = kthread_run(cmm_thread, NULL, "cmmthread"); if (IS_ERR(cmm_thread_ptr)) { rc = PTR_ERR(cmm_thread_ptr); - goto out_unregister_sysfs; + goto out_unregister_notifier; } return rc; -out_unregister_sysfs: +out_unregister_notifier: + unregister_memory_notifier(&cmm_mem_nb); + unregister_memory_isolate_notifier(&cmm_mem_isolate_nb); cmm_unregister_sysfs(&cmm_sysdev); out_reboot_notifier: unregister_reboot_notifier(&cmm_reboot_nb); @@ -458,6 +698,8 @@ static void cmm_exit(void) kthread_stop(cmm_thread_ptr); unregister_oom_notifier(&cmm_oom_nb); unregister_reboot_notifier(&cmm_reboot_nb); + unregister_memory_notifier(&cmm_mem_nb); + unregister_memory_isolate_notifier(&cmm_mem_isolate_nb); cmm_free_pages(loaned_pages); cmm_unregister_sysfs(&cmm_sysdev); }