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Wed, 14 Oct 2026 19:04:07 -0700 (PDT) Received: from google.com ([2a00:79e0:2031:6:8455:7899:5a2e:26f8]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3ac94748c6csm1889088a91.10.2026.10.14.19.04.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 14 Oct 2026 19:04:06 -0700 (PDT) Date: Thu, 15 Oct 2026 11:04:03 +0900 From: Sergey Senozhatsky To: Barry Song Cc: Bo Zhang , senozhatsky@chromium.org, 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: <20261013035201.2809924-11-senozhatsky@chromium.org> <20261014153603.1365617-1-zhangbo56@xiaomi.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: eqpru4bcsd5snho5p4kde8qgu7mcswn4 X-Rspamd-Queue-Id: B5E191C0007 X-Rspam-User: X-Rspamd-Server: rspam02 X-HE-Tag: 1792029848-386144 X-HE-Meta: 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 onyANlwX PS6Jr/5JO7VHeCAwXCeMseHeLHLC72XBHawMR3oFI8HFjO2Q//iGD6FJaR21HsfxgYQ1rY/eDaZ4vm7oq8X5eKOpep+nbZI6uepnHJrLh5ZybTq6v2EXuNaBMeC4plBVIKYWIWbyQvdHvQ/rgaVZY0XIqdBMWLabO7fwGUXJrIHgalYEETEJL70niYOnICj87bmpVJbTZFRET6RYPYCiCh/ZsKTIYo02+cdUXEoohKyVB9Med6QXdfemqIZxzsKtuVWzEaFlbwWPPbqW9GK0bbZzoBg53UUGDZAV4W4eUn1xFLmi8FX36T2MIN2Ua7eZ15Yma/5F7e32NMySV7aIvrmYvm7fPqd3itXmrhPDhICz2psx3s4DqnTXEokj8rFJJmtKZzB0x+WYJkCHKHihkINmcpA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On (26/10/15 04:46), Barry Song wrote: > Also, with either deflate or zstd, create_dctx() will > always be present. So, what algorithm are we actually testing? > What happens if we switch to zstd? Right. Am not that concerned with deflate, but seeing zstd on that list is a tad sad. zstd mutates decompression ctx, so it cannot be shared. On the other hand, zstd_dctx_workspace_bound() is almost 100KB so allocating dctx per-read request will be rather problematic.