From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 E4BA5CA5A for ; Wed, 6 Nov 2024 00:33:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730853235; cv=none; b=ghElkLKdMd0srOtbaggK4YrLFiksf42TCeVv7Vem/ArBxF20pb28rBME3zxPaDuBhpdDLBCGGs0BxDIrd5p9US1QRoqdQycD5Km6GUpPcVMlNF9NfKWfb+SuaitYhJEeGkCHIWZnferntSzwgLCVVFrxglI9/5QK81GNL9UgaRQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730853235; c=relaxed/simple; bh=3wzrMsXrDoCgqEE7p0Ouhq3heGwPmfe/6ZEZcV3rZ30=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=F6PS+4BAaASBqooRYW20nmxMg0GhYflQyK8DtNOjXLgJBNZIdLKPhdu/UHCq/d+wZeigyjuw8yJ5Xj+Put32HJ3A6LI0omOJkGYzyByz8jDvnSg5wx0Zj+upPmBLCCiRFWUC3rTItP2kIqpvtXfKUQLqL2KgbNaKEwKxs9pEEr4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=i6YLLdSd; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="i6YLLdSd" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7488AC4CECF; Wed, 6 Nov 2024 00:33:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1730853234; bh=3wzrMsXrDoCgqEE7p0Ouhq3heGwPmfe/6ZEZcV3rZ30=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=i6YLLdSdGnXazWUPcIZMvdt7QYyaH0lgO6PK7n91NIVsAv+pSlUhzfDc9oU9TjqFJ GZvzuhSLi+WGCYUL+C7EkvX+5Aeg3veoWfvM0qHUkVbUe5m/fql0IMGyit6DySqgOV 6odUNJ7BttHJAOMXAQ+6NFuaTcARhjO0c2p6zAow5YH91cOsZClVVxeUnWe8hdOZ6/ tj5DraFctPajzGbGOv6KvAvyQvSmBrx+mB16lQzb8RJz0tRn+8ygQODoENPdx0nfrV x2qh1F9pApflyuFPScLlI0R/drzMkFGwmgaZ32UndkmavY90FywmDGgV2XhZ5ifAPf xzDMEJCV8ndMQ== Date: Tue, 5 Nov 2024 14:33:53 -1000 From: Tejun Heo To: Andrea Righi Cc: David Vernet , linux-kernel@vger.kernel.org Subject: Re: [PATCH sched_ext/for-6.13] sched_ext: Do not enable LLC/NUMA optimizations when domains overlap Message-ID: References: <20241031073401.13034-1-arighi@nvidia.com> Precedence: bulk X-Mailing-List: linux-kernel@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: Hello, On Wed, Nov 06, 2024 at 01:29:08AM +0100, Andrea Righi wrote: ... > Let's say we have 2 NUMA nodes, each with 2 sockets, and each socket > has its own L3 cache. In this case, numa_cpus will be larger than > llc_cpus, and enabling both NUMA and LLC optimizations would be > beneficial. > > On the other hand, if each NUMA node contains only 1 socket, numa_cpus > and llc_cpus will overlap completely, making it unnecessary to enable > both NUMA and LLC optimizations, so we can have just the LLC in this > case. > > Would something like this help clarifying the first test? I was more thinking about the theoretical case where one socket has one LLC while a different socket has multiple LLCs. I don't think there are any systems which are actually like that but there's nothing in the code which prevents that (unlike a single CPU belonging to multiple domains), so it'd probably be worthwhile to explain why the abbreviated test is enough. Thanks. -- tejun