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Thu, 15 Oct 2026 20:13:44 -0700 (PDT) Received: from google.com ([2a00:79e0:2031:6:a579:8b87:8304:7ac2]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-89f54b2eec9sm406056b3a.8.2026.10.15.20.13.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 15 Oct 2026 20:13:42 -0700 (PDT) Date: Fri, 16 Oct 2026 12:13:39 +0900 From: Sergey Senozhatsky To: Barry Song Cc: Sergey Senozhatsky , Bo Zhang , akpm@linux-foundation.org, bgeffon@google.com, minchan@kernel.org, richardycc@google.com, linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v3 10/11] zram: use rw_semaphore for decompression streams Message-ID: References: <20261015112440.1491168-1-zhangbo56@xiaomi.com> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Hi, On (26/10/16 11:10), Barry Song wrote: > > > I applied the kmalloc+memcpy variant on-device and re-ran the same > > > Android A/B. It removes the exclusive path entirely in our workload. > > > > > > 9+10 9+10 + kmalloc fastpath > > > read contended ~1,959 0 > > > read wait_ns total ~12 s 0 > > > read wait_ns max 72-96 ms 0 > > > shared 76.7% 100% > > > exclusive 23.3% 0% > > > dpin_contended 0 0 > > > > > > Every decompression now takes the shared (down_read) path, including the > > > cross-page objects that previously had to go exclusive. The ~1,959 > > > residual contentions on the exclusive path are gone, and pin contention > > > stays at zero, so the full read side runs concurrently with no stream > > > contention. > > > > > > Read-side contention end to end: > > > > > > baseline 9+10 9+10 + kmalloc > > > read contended 24,749 ~1,959 0 > > > shared 0% 76.7% 100% > > > > Thank you. I'll include kmalloc patch to v4 of the series. > > Hi Sergey, Bo, > > I assume when Sergey sent v4, could tag for the patchset with > > Tested-by: Bo Zhang That would be great. > also, Bo's data can be put in cover-letter? Sure, I can include it, along with my numbers.