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Howlett" References: <20260516-sheaves-tuning-v1-0-221aa3e1d829@kernel.org> <20260516-sheaves-tuning-v1-6-221aa3e1d829@kernel.org> From: "Harry Yoo (Oracle)" In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 4BBB41C0003 X-Stat-Signature: n1imo51suzg6pmm9c34jey1kiw697owc X-Rspam-User: X-HE-Tag: 1779087218-325125 X-HE-Meta: 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 jB6QNzI/ xugFIqUZb3pbfCyC68oMNBz46/50aNw04GnbfGH73glIhCnWeC9fYYF+l3CoQmG8al5tqP/DnxErS8xMnoqFyrsVr6mP6r2hw+Vrz9hPPw4YkJX6+ivC6APBvPrG9ruwQ3IJm3m31JN2c1wJXLJh/qfvzDmf9LvzPoIq2p/5cJAeR/HvTkZXpiU/I2nLDFGUbnGjkzv8Fi87glwtExEv722xmxUkIUE6y2+1BtqlzmbwRpNyK23yu3Ue3xZ8pSmtQ8XGnSqYlgpRTaUYWXc93x+C4L7CumVWnpRVHz2GLqKktwNW1BMPBHWdtDmgX+rKFS32kyN+uyJiYbBA= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 5/17/26 5:30 PM, Yeoreum Yun wrote: > Hi Harry, Hi Yeoreum, >> @@ -9111,7 +9309,39 @@ static ssize_t sheaf_capacity_show(struct kmem_cache *s, char *buf) >> { >> return sysfs_emit(buf, "%hu\n", s->sheaf_capacity); >> } >> -SLAB_ATTR_RO(sheaf_capacity); >> +static ssize_t sheaf_capacity_store(struct kmem_cache *s, >> + const char *buf, size_t length) >> +{ >> + unsigned short capacity; >> + int err; >> + >> + err = kstrtou16(buf, 10, &capacity); >> + if (err) >> + return err; >> + >> + if (!cache_supports_sheaves(s)) >> + return -EOPNOTSUPP; >> + >> + cpus_read_lock(); >> + mutex_lock(&slab_mutex); > > This patchset looks good to me. Thanks :) > However, I’m not sure why we need slab_mutex here, as using only > flush_lock seems sufficient The main reason why I used slab_mutex was because both disabling sheaves and shrinking the cache acquires flush_lock. > Some refactoring might be required, but it seems better to remove > the acquisition of slab_mutex here. With some refactoring, we could teach those functions that the caller already acquired the lock and use flush_lock instead of slab_mutex. However, it won't improve things much... both are global locks, and I doubt that it would cause visible latency issues when creating new slab caches. I want to focus on refining the capacity change part for now. -- Cheers, Harry / Hyeonggon