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Thu, 5 Sep 2019 14:46:08 -0700 Received: by devvm2643.prn2.facebook.com (Postfix, from userid 111017) id B7F3917229E02; Thu, 5 Sep 2019 14:46:06 -0700 (PDT) Smtp-Origin-Hostprefix: devvm From: Roman Gushchin Smtp-Origin-Hostname: devvm2643.prn2.facebook.com To: CC: Michal Hocko , Johannes Weiner , , , Shakeel Butt , Vladimir Davydov , Waiman Long , Roman Gushchin Smtp-Origin-Cluster: prn2c23 Subject: [PATCH RFC 06/14] mm: slub: implement SLUB version of obj_to_index() Date: Thu, 5 Sep 2019 14:45:50 -0700 Message-ID: <20190905214553.1643060-7-guro@fb.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190905214553.1643060-1-guro@fb.com> References: <20190905214553.1643060-1-guro@fb.com> X-FB-Internal: Safe MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.70,1.0.8 definitions=2019-09-05_08:2019-09-04,2019-09-05 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 malwarescore=0 lowpriorityscore=0 spamscore=0 priorityscore=1501 phishscore=0 mlxlogscore=840 mlxscore=0 clxscore=1015 adultscore=0 suspectscore=3 impostorscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-1906280000 definitions=main-1909050203 X-FB-Internal: deliver X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: This commit implements SLUB version of the obj_to_index() function, which will be required to calculate the offset of memcg_ptr in the mem_cgroup_vec to store/obtain the memcg ownership data. To make it faster, let's repeat the SLAB's trick introduced by commit 6a2d7a955d8d ("[PATCH] SLAB: use a multiply instead of a divide in obj_to_index()") and avoid an expensive division. Signed-off-by: Roman Gushchin --- include/linux/slub_def.h | 9 +++++++++ mm/slub.c | 1 + 2 files changed, 10 insertions(+) diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h index d2153789bd9f..200ea292f250 100644 --- a/include/linux/slub_def.h +++ b/include/linux/slub_def.h @@ -8,6 +8,7 @@ * (C) 2007 SGI, Christoph Lameter */ #include +#include enum stat_item { ALLOC_FASTPATH, /* Allocation from cpu slab */ @@ -86,6 +87,7 @@ struct kmem_cache { unsigned long min_partial; unsigned int size; /* The size of an object including metadata */ unsigned int object_size;/* The size of an object without metadata */ + struct reciprocal_value reciprocal_size; unsigned int offset; /* Free pointer offset */ #ifdef CONFIG_SLUB_CPU_PARTIAL /* Number of per cpu partial objects to keep around */ @@ -182,4 +184,11 @@ static inline void *nearest_obj(struct kmem_cache *cache, struct page *page, return result; } +static inline unsigned int obj_to_index(const struct kmem_cache *cache, + const struct page *page, void *obj) +{ + return reciprocal_divide(kasan_reset_tag(obj) - page_address(page), + cache->reciprocal_size); +} + #endif /* _LINUX_SLUB_DEF_H */ diff --git a/mm/slub.c b/mm/slub.c index 3014158c100d..b043cfb673c9 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -3587,6 +3587,7 @@ static int calculate_sizes(struct kmem_cache *s, int forced_order) */ size = ALIGN(size, s->align); s->size = size; + s->reciprocal_size = reciprocal_value(size); if (forced_order >= 0) order = forced_order; else