Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764663AbZLQM3T (ORCPT ); Thu, 17 Dec 2009 07:29:19 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756877AbZLQM3T (ORCPT ); Thu, 17 Dec 2009 07:29:19 -0500 Received: from mx1.redhat.com ([209.132.183.28]:29487 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756806AbZLQM3Q (ORCPT ); Thu, 17 Dec 2009 07:29:16 -0500 Message-ID: <4B2A22C0.8080001@redhat.com> Date: Thu, 17 Dec 2009 07:23:28 -0500 From: Larry Woodman Reply-To: lwoodman@redhat.com Organization: RedHat User-Agent: Thunderbird 2.0.0.21 (X11/20090320) MIME-Version: 1.0 To: KOSAKI Motohiro CC: Rik van Riel , LKML , akpm@linux-foundation.org, linux-mm Subject: FWD: [PATCH v2] vmscan: limit concurrent reclaimers in shrink_zone References: <20091211164651.036f5340@annuminas.surriel.com> <1260810481.6666.13.camel@dhcp-100-19-198.bos.redhat.com> <20091217193818.9FA9.A69D9226@jp.fujitsu.com> In-Reply-To: <20091217193818.9FA9.A69D9226@jp.fujitsu.com> Content-Type: multipart/mixed; boundary="------------060208050503010206050303" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 9202 Lines: 282 This is a multi-part message in MIME format. --------------060208050503010206050303 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit KOSAKI Motohiro wrote: > (offlist) > > Larry, May I ask current status of following your issue? > I don't reproduce it. and I don't hope to keep lots patch are up in the air. > Yes, sorry for the delay but I dont have direct or exclusive access to these large systems and workloads. As far as I can tell this patch series does help prevent total system hangs running AIM7. I did have trouble with the early postings mostly due to using sleep_on() and wakeup() but those appear to be fixed. However, I did add more debug code and see ~10000 processes blocked in shrink_zone_begin(). This is expected but bothersome, practically all of the processes remain runnable for the entire duration of these AIM runs. Collectively all these runnable processes overwhelm the VM system. There are many more runnable processes now than were ever seen before, ~10000 now versus ~100 on RHEL5(2.6.18 based). So, we have also been experimenting around with some of the CFS scheduler tunables to see of this is responsible... > plus, I integrated page_referenced() improvement patch series and > limit concurrent reclaimers patch series privately. I plan to post it > to lkml at this week end. comments are welcome. > The only problem I noticed with the page_referenced patch was an increase in the try_to_unmap() failures which causes more re-activations. This is very obvious with the using tracepoints I have posted over the past few months but they were never included. I didnt get a chance to figure out the exact cause due to access to the hardware and workload. This patch series also seems to help the overall stalls in the VM system. > > changelog from last post: > - remake limit concurrent reclaimers series and sort out its patch order > - change default max concurrent reclaimers from 8 to num_online_cpu(). > it mean, Andi only talked negative feeling comment in last post. > he dislike constant default value. plus, over num_online_cpu() is > really silly. iow, it is really low risk. > (probably we might change default value. as far as I mesure, small > value makes better benchmark result. but I'm not sure small value > don't make regression) > - Improve OOM and SIGKILL behavior. > (because RHEL5's vmscan has TIF_MEMDIE recovering logic, but > current mainline doesn't. I don't hope RHEL6 has regression) > > > > >> On Fri, 2009-12-11 at 16:46 -0500, Rik van Riel wrote: >> >> Rik, the latest patch appears to have a problem although I dont know >> what the problem is yet. When the system ran out of memory we see >> thousands of runnable processes and 100% system time: >> >> >> 9420 2 29824 79856 62676 19564 0 0 0 0 8054 379 0 >> 100 0 0 0 >> 9420 2 29824 79368 62292 19564 0 0 0 0 8691 413 0 >> 100 0 0 0 >> 9421 1 29824 79780 61780 19820 0 0 0 0 8928 408 0 >> 100 0 0 0 >> >> The system would not respond so I dont know whats going on yet. I'll >> add debug code to figure out why its in that state as soon as I get >> access to the hardware. >> This was in response to Rik's first patch and seems to be fixed by the latest path set. Finally, having said all that, the system still struggles reclaiming memory with ~10000 processes trying at the same time, you fix one bottleneck and it moves somewhere else. The latest run showed all but one running process spinning in page_lock_anon_vma() trying for the anon_vma_lock. I noticed that there are ~5000 vma's linked to one anon_vma, this seems excessive!!! I changed the anon_vma->lock to a rwlock_t and page_lock_anon_vma() to use read_lock() so multiple callers could execute the page_reference_anon code. This seems to help quite a bit. >> Larry --------------060208050503010206050303 Content-Type: text/x-patch; name="aim.patch" Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="aim.patch" diff --git a/include/linux/rmap.h b/include/linux/rmap.h index cb0ba70..6b32ecf 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -25,7 +25,7 @@ * pointing to this anon_vma once its vma list is empty. */ struct anon_vma { - spinlock_t lock; /* Serialize access to vma list */ + rwlock_t lock; /* Serialize access to vma list */ /* * NOTE: the LSB of the head.next is set by * mm_take_all_locks() _after_ taking the above lock. So the @@ -43,14 +43,14 @@ static inline void anon_vma_lock(struct vm_area_struct *vma) { struct anon_vma *anon_vma = vma->anon_vma; if (anon_vma) - spin_lock(&anon_vma->lock); + write_lock(&anon_vma->lock); } static inline void anon_vma_unlock(struct vm_area_struct *vma) { struct anon_vma *anon_vma = vma->anon_vma; if (anon_vma) - spin_unlock(&anon_vma->lock); + write_unlock(&anon_vma->lock); } /* diff --git a/mm/migrate.c b/mm/migrate.c index 7dbcb22..3f0305b 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -183,12 +183,12 @@ static void remove_anon_migration_ptes(struct page *old, struct page *new) * We hold the mmap_sem lock. So no need to call page_lock_anon_vma. */ anon_vma = (struct anon_vma *) (mapping - PAGE_MAPPING_ANON); - spin_lock(&anon_vma->lock); + write_lock(&anon_vma->lock); list_for_each_entry(vma, &anon_vma->head, anon_vma_node) remove_migration_pte(vma, old, new); - spin_unlock(&anon_vma->lock); + write_unlock(&anon_vma->lock); } /* diff --git a/mm/mmap.c b/mm/mmap.c index 814b95f..42324cb 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -592,7 +592,7 @@ again: remove_next = 1 + (end > next->vm_end); if (vma->anon_vma && (insert || importer || start != vma->vm_start)) anon_vma = vma->anon_vma; if (anon_vma) { - spin_lock(&anon_vma->lock); + write_lock(&anon_vma->lock); /* * Easily overlooked: when mprotect shifts the boundary, * make sure the expanding vma has anon_vma set if the @@ -646,7 +646,7 @@ again: remove_next = 1 + (end > next->vm_end); } if (anon_vma) - spin_unlock(&anon_vma->lock); + write_unlock(&anon_vma->lock); if (mapping) spin_unlock(&mapping->i_mmap_lock); @@ -2442,7 +2442,7 @@ static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma) * The LSB of head.next can't change from under us * because we hold the mm_all_locks_mutex. */ - spin_lock_nest_lock(&anon_vma->lock, &mm->mmap_sem); + write_lock(&anon_vma->lock); /* * We can safely modify head.next after taking the * anon_vma->lock. If some other vma in this mm shares @@ -2558,7 +2558,7 @@ static void vm_unlock_anon_vma(struct anon_vma *anon_vma) if (!__test_and_clear_bit(0, (unsigned long *) &anon_vma->head.next)) BUG(); - spin_unlock(&anon_vma->lock); + write_unlock(&anon_vma->lock); } } diff --git a/mm/rmap.c b/mm/rmap.c index dd43373..abddf95 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -116,7 +116,7 @@ int anon_vma_prepare(struct vm_area_struct *vma) return -ENOMEM; allocated = anon_vma; } - spin_lock(&anon_vma->lock); + write_lock(&anon_vma->lock); /* page_table_lock to protect against threads */ spin_lock(&mm->page_table_lock); @@ -127,7 +127,7 @@ int anon_vma_prepare(struct vm_area_struct *vma) } spin_unlock(&mm->page_table_lock); - spin_unlock(&anon_vma->lock); + write_unlock(&anon_vma->lock); if (unlikely(allocated)) anon_vma_free(allocated); } @@ -153,9 +153,9 @@ void anon_vma_link(struct vm_area_struct *vma) struct anon_vma *anon_vma = vma->anon_vma; if (anon_vma) { - spin_lock(&anon_vma->lock); + write_lock(&anon_vma->lock); list_add_tail(&vma->anon_vma_node, &anon_vma->head); - spin_unlock(&anon_vma->lock); + write_unlock(&anon_vma->lock); } } @@ -167,12 +167,12 @@ void anon_vma_unlink(struct vm_area_struct *vma) if (!anon_vma) return; - spin_lock(&anon_vma->lock); + write_lock(&anon_vma->lock); list_del(&vma->anon_vma_node); /* We must garbage collect the anon_vma if it's empty */ empty = list_empty(&anon_vma->head); - spin_unlock(&anon_vma->lock); + write_unlock(&anon_vma->lock); if (empty) anon_vma_free(anon_vma); @@ -182,7 +182,7 @@ static void anon_vma_ctor(void *data) { struct anon_vma *anon_vma = data; - spin_lock_init(&anon_vma->lock); + rwlock_init(&anon_vma->lock); INIT_LIST_HEAD(&anon_vma->head); } @@ -209,7 +209,7 @@ struct anon_vma *page_lock_anon_vma(struct page *page) goto out; anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON); - spin_lock(&anon_vma->lock); + read_lock(&anon_vma->lock); return anon_vma; out: rcu_read_unlock(); @@ -218,7 +218,7 @@ out: void page_unlock_anon_vma(struct anon_vma *anon_vma) { - spin_unlock(&anon_vma->lock); + read_unlock(&anon_vma->lock); rcu_read_unlock(); } --------------060208050503010206050303-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/