From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta0.migadu.com (out-64.mta0.migadu.com [91.218.175.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5AE9C356779 for ; Tue, 25 Aug 2026 22:06:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.64 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787695584; cv=none; b=HcxZQM3vRuXxqAzMMpVf2xLMNy+grEbcpWvjVf9KsddCdxsIZ1Q8FIj6I8dzFKxlnwA7OHyPvjDN00YHvHV5pFIxATU3aHQGzgWe8rOEv6yhhlwY5pAwR+zR6z4kfTiblv84JuOxsD/oav61non+p0G44GAlN7Ht1ZVlm3qKBAs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787695584; c=relaxed/simple; bh=gFBOFMo679ZDXmdW0dMMgBbOdsuuqwAEoQO4bDPF8do=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=f07j08UrWlsR9yi7YrYz79dWc+X1Q0msIbvte7pZ2KdEXhLPWcaf4C2z7nai0iUWeR0KH82oLMeTnlJwKudBTVn+xKg3+wDN3RJPH5/FNjUMB1xCgzBBRLW3FJJ3h6sIhwDjLgO1az0okgfsTHE8uq46R6NMx+IdUXqnCtDe9z0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=tM6eKWYI; arc=none smtp.client-ip=91.218.175.64 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="tM6eKWYI" X-Envelope-To: linux-crypto@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=gFBOFMo679ZDXmdW0dMMgBbOdsuuqwAEoQO4bDPF8do=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1787695579; v=1; x=1788300379; b=tM6eKWYIiJlhYEjy4SDfYYjRJ0QhjipFJbNjAcsup1cX++HrwbUahKAvLrkS9CBdgZpH0GXO tTqRhboFz1a2pee4GqWTZrvNXSBkdDkQtzyJsOSiwEw4MIIBeRt7VXC+Hr2Wh2yqxPcHgQTgLwd nFaC3pjjTXPEfQozto+1MZOE= X-Envelope-To: linux-crypto@vger.kernel.org Received: from localhost (2a03:2880:10ff:59::) by mta10.migadu.com with ESMTPS id 6a51ded681de72a3; Tue, 25 Aug 2026 22:06:19 +0000 X-Mizu-Trace-ID: 6a51ded681de72a3 X-Migadu-Flow: FLOW_OUT From: Usama Arif To: davem@davemloft.net, dsterba@suse.com, Herbert Xu , linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org, terrelln@fb.com Cc: hannes@cmpxchg.org, yosry@kernel.org, nphamcs@gmail.com, chengming.zhou@linux.dev, shakeel.butt@linux.dev, kernel-team@meta.com, Usama Arif Subject: [PATCH 0/2] crypto: zstd - avoid initializing the workspace twice Date: Tue, 25 Aug 2026 15:06:00 -0700 Message-ID: <20260825220616.3842633-1-usama.arif@linux.dev> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: linux-crypto@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Both zstd_compress() and zstd_decompress() set up the shared per-CPU workspace as a C/DStream before walking the request, and then, when the first source and destination fragments each span the whole request, hand off to zstd_compress_one()/zstd_decompress_one(), which immediately overwrite that same ctx->wksp with a CCtx/DCtx. The stream setup is discarded without a byte having been processed. That one-shot path is not a corner case: zswap always takes it when storing, and takes it for a load whenever the stored object lies within a single zsmalloc page. These two patches defer the stream initialization to the first walk iteration that actually streams, guarded by a flag because that iteration can be reached more than once. A 4 KiB crypto_acomp benchmark [1], twelve runs of nine 30,000-operation rounds. Bare metal is an Intel Xeon Platinum 8321HC, turbo off, performance governor, pinned to one core; the VM is a one-vCPU KVM guest on a faster host. baseline patched delta bare metal compress 52,283 ns 51,038 ns 1,245 ns 2.4% decompress 2,317 ns 1,998 ns 319 ns 13.8% one-vCPU KVM compress 16,675 ns 15,050 ns 1,625 ns 9.8% decompress 3,516 ns 2,265 ns 1,251 ns 35.6% The guest numbers are larger because the two CPUID instructions in ZSTD_cpuid() become unconditional VM exits there. [1] https://gist.github.com/uarif1/5cf02f0e22c23f0d1b3d84348f12914c Usama Arif (2): crypto: zstd - Avoid redundant cstream initialization crypto: zstd - Avoid redundant dstream initialization crypto/zstd.c | 40 ++++++++++++++++++++++++++++------------ 1 file changed, 28 insertions(+), 12 deletions(-) base-commit: 4b18edbd8e70f7e6860d56370f13244896d0f95c -- 2.53.0-Meta