Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935880Ab2KAMKV (ORCPT ); Thu, 1 Nov 2012 08:10:21 -0400 Received: from mailhub.sw.ru ([195.214.232.25]:14230 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935769Ab2KAMH4 (ORCPT ); Thu, 1 Nov 2012 08:07:56 -0400 From: Glauber Costa To: Cc: , Andrew Morton , , Johannes Weiner , Tejun Heo , Michal Hocko , Christoph Lameter , Pekka Enberg , David Rientjes , Glauber Costa , Pekka Enberg , Suleiman Souhlal Subject: [PATCH v6 28/29] slub: slub-specific propagation changes. Date: Thu, 1 Nov 2012 16:07:44 +0400 Message-Id: <1351771665-11076-29-git-send-email-glommer@parallels.com> X-Mailer: git-send-email 1.7.11.7 In-Reply-To: <1351771665-11076-1-git-send-email-glommer@parallels.com> References: <1351771665-11076-1-git-send-email-glommer@parallels.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5462 Lines: 173 SLUB allows us to tune a particular cache behavior with sysfs-based tunables. When creating a new memcg cache copy, we'd like to preserve any tunables the parent cache already had. This can be done by tapping into the store attribute function provided by the allocator. We of course don't need to mess with read-only fields. Since the attributes can have multiple types and are stored internally by sysfs, the best strategy is to issue a ->show() in the root cache, and then ->store() in the memcg cache. The drawback of that, is that sysfs can allocate up to a page in buffering for show(), that we are likely not to need, but also can't guarantee. To avoid always allocating a page for that, we can update the caches at store time with the maximum attribute size ever stored to the root cache. We will then get a buffer big enough to hold it. The corolary to this, is that if no stores happened, nothing will be propagated. It can also happen that a root cache has its tunables updated during normal system operation. In this case, we will propagate the change to all caches that are already active. Signed-off-by: Glauber Costa CC: Christoph Lameter CC: Pekka Enberg CC: Michal Hocko CC: Kamezawa Hiroyuki CC: Johannes Weiner CC: Suleiman Souhlal CC: Tejun Heo --- include/linux/slub_def.h | 1 + mm/slub.c | 76 +++++++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 76 insertions(+), 1 deletion(-) diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h index 364ba6c..9db4825 100644 --- a/include/linux/slub_def.h +++ b/include/linux/slub_def.h @@ -103,6 +103,7 @@ struct kmem_cache { #endif #ifdef CONFIG_MEMCG_KMEM struct memcg_cache_params *memcg_params; + int max_attr_size; /* for propagation, maximum size of a stored attr */ #endif #ifdef CONFIG_NUMA diff --git a/mm/slub.c b/mm/slub.c index ffc8ede..6c39af8 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -203,13 +203,14 @@ enum track_item { TRACK_ALLOC, TRACK_FREE }; static int sysfs_slab_add(struct kmem_cache *); static int sysfs_slab_alias(struct kmem_cache *, const char *); static void sysfs_slab_remove(struct kmem_cache *); - +static void memcg_propagate_slab_attrs(struct kmem_cache *s); #else static inline int sysfs_slab_add(struct kmem_cache *s) { return 0; } static inline int sysfs_slab_alias(struct kmem_cache *s, const char *p) { return 0; } static inline void sysfs_slab_remove(struct kmem_cache *s) { } +static inline void memcg_propagate_slab_attrs(struct kmem_cache *s) { } #endif static inline void stat(const struct kmem_cache *s, enum stat_item si) @@ -3955,6 +3956,7 @@ int __kmem_cache_create(struct kmem_cache *s, unsigned long flags) if (err) return err; + memcg_propagate_slab_attrs(s); mutex_unlock(&slab_mutex); err = sysfs_slab_add(s); mutex_lock(&slab_mutex); @@ -5180,6 +5182,7 @@ static ssize_t slab_attr_store(struct kobject *kobj, struct slab_attribute *attribute; struct kmem_cache *s; int err; + int i __maybe_unused; attribute = to_slab_attr(attr); s = to_slab(kobj); @@ -5188,10 +5191,81 @@ static ssize_t slab_attr_store(struct kobject *kobj, return -EIO; err = attribute->store(s, buf, len); +#ifdef CONFIG_MEMCG_KMEM + if (slab_state < FULL) + return err; + if ((err < 0) || !is_root_cache(s)) + return err; + + mutex_lock(&slab_mutex); + if (s->max_attr_size < len) + s->max_attr_size = len; + + for_each_memcg_cache_index(i) { + struct kmem_cache *c = cache_from_memcg(s, i); + if (c) + /* return value determined by the parent cache only */ + attribute->store(c, buf, len); + } + mutex_unlock(&slab_mutex); +#endif return err; } +static void memcg_propagate_slab_attrs(struct kmem_cache *s) +{ +#ifdef CONFIG_MEMCG_KMEM + int i; + char *buffer = NULL; + + if (!is_root_cache(s)) + return; + + /* + * This mean this cache had no attribute written. Therefore, no point + * in copying default values around + */ + if (!s->max_attr_size) + return; + + for (i = 0; i < ARRAY_SIZE(slab_attrs); i++) { + char mbuf[64]; + char *buf; + struct slab_attribute *attr = to_slab_attr(slab_attrs[i]); + + if (!attr || !attr->store || !attr->show) + continue; + + /* + * It is really bad that we have to allocate here, so we will + * do it only as a fallback. If we actually allocate, though, + * we can just use the allocated buffer until the end. + * + * Most of the slub attributes will tend to be very small in + * size, but sysfs allows buffers up to a page, so they can + * theoretically happen. + */ + if (buffer) + buf = buffer; + else if (s->max_attr_size < ARRAY_SIZE(mbuf)) + buf = mbuf; + else { + buffer = (char *) get_zeroed_page(GFP_KERNEL); + if (WARN_ON(!buffer)) + continue; + buf = buffer; + } + + attr->show(s->memcg_params->root_cache, buf); + attr->store(s, buf, strlen(buf)); + } + + if (buffer) + free_page((unsigned long)buffer); +#endif +} + static const struct sysfs_ops slab_sysfs_ops = { .show = slab_attr_show, .store = slab_attr_store, -- 1.7.11.7 -- 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/