From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from stravinsky.debian.org (stravinsky.debian.org [82.195.75.108]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5D285373BF3; Wed, 17 Jun 2026 17:40:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=82.195.75.108 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781718011; cv=none; b=g5nCsP9CABWbmRBrG1KPfIGZhzGGdfN/Rkmaal3xi6DePvYdCCVFTTVdcnMtQeB0jvgDngQq0Bacl1xS+oXbbkgkDEKLAXaZvLBmxOmXZGmYOhgXOMM5+zgQkuKx15vhcOpcyLmHrwaFfNUyswdgJ4rw/ELDP6aOrphURr/yQ8g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781718011; c=relaxed/simple; bh=Q3EppVyIAzldDQeHiU3GGZ6sXK225mcvQcRPFOwTh4g=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=nK3VKIeWZuo0xlchCob1fRNVt1eYue0A7nJkfD+X0lhPKWKLRMfrsVRzoYzTYNPP01Ur/RwecGG8TuvU6dx4wDmd0xNThYtLqdc+Lu1bC5ivkDScjZlGiCVaAAjOtsMbcUWI1ctfN2+KHNR8McT2wNdU4/akr1g1HftQxjL9fJI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=debian.org; spf=pass smtp.mailfrom=debian.org; dkim=pass (2048-bit key) header.d=debian.org header.i=@debian.org header.b=nP/QGtCh; arc=none smtp.client-ip=82.195.75.108 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=debian.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=debian.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=debian.org header.i=@debian.org header.b="nP/QGtCh" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=debian.org; s=smtpauto.stravinsky; h=X-Debian-User:In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=PcW4yhsbJNIlOdOi8liKCG9YkTC2sUqTdvuc+EIeHNc=; b=nP/QGtChpgkRPa4/SQ1WwGzAC3 92Tq4lsvWGLvQipc2LHXpzFKKDCVup7fngr5gP9iK5DEpXVcHOK75kx0ZFGs2i0oESJ9mk/AhMTU0 avBN/ST7/fmpTnNUZy0ASqFhyi256Gt5Mik9OFXOKn+l9FqupYfVuyA0Er157yVUY6ErcGi+29LUu 9teT0zOZUz3orDT1lvy/WRA8t9SEfbQbRR7l4FDOsQWlmsskSoxL8z+8Gl3AGxgabwTEM7uP2XfLh lF9HUVtbqZeC519k4dzQALFlQuEuWa3a69blcLT47+c7ZV/RjIxEx+y3JqAV8v/d2PtYd+haO+2l3 m8+O9v9w==; Received: from authenticated-user by stravinsky.debian.org with esmtpsa (TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.96) (envelope-from ) id 1wZuF1-00EmvQ-16; Wed, 17 Jun 2026 17:39:55 +0000 Date: Wed, 17 Jun 2026 10:39:49 -0700 From: Breno Leitao To: Mateusz Guzik Cc: Oleg Nesterov , Josh Triplett , Alexander Viro , Christian Brauner , Jan Kara , Shuah Khan , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, shakeel.butt@linux.dev, jlayton@kernel.org, axboe@kernel.dk, kernel-team@meta.com Subject: Re: [PATCH v3 0/2] fs/pipe: reduce pipe->mutex contention by pre-allocating outside the lock Message-ID: References: <20260524-fix_pipe-v3-0-bb4a75d23a90@debian.org> Precedence: bulk X-Mailing-List: linux-fsdevel@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: X-Debian-User: leitao On Wed, Jun 17, 2026 at 05:01:04PM +0200, Mateusz Guzik wrote: > On Wed, Jun 17, 2026 at 03:23:54AM -0700, Breno Leitao wrote: > > Measured it to _just be sure_, 1-byte ping-pong (perf bench sched pipe -s 1): > > > > baseline: 2.674 usecs/op > > patched: 2.710 usecs/op (+1.3%, within run-to-run noise) > > > > Can you try this: I've tested this change, but the results show no real measurable improvement beyond measurement noise. patched + your change: ~2.66 usecs/op (-1.7%, within noise) In my experience, branch hints haven't proven particularly effective, at least that was the case when I worked on PowerPC some time ago.