From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 0181CCAC58D for ; Thu, 11 Sep 2025 09:33:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:MIME-Version: Content-Transfer-Encoding:Content-Type:References:In-Reply-To:Date:Cc:To:From :Subject:Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=6zJl6jcafeCZ6YmJZKiwF1mOHdjn2LFeup/aII/uTkE=; b=t5O3zupAz3rAb9qxKh6YTwTaoX hSoQH/MjoDxP2c4dCq0gDeRYbJq+7ukJcQssagyLwxXsMBAR5TuiII26uXASvcl0K5/k2nRkIf3CD eL+GIr0AuRN9i6AYluaeZMrzI38GUKHTtM/yWdJSCjbF8uz+6B3Ip8KYI1LLBo9POVPmdiX0ZY12R qT0kaN1iiksCUgCs03K6XynS8lbymqsSczS1sz+Kd50qT1VHAExR/8Bt84eA09x6uDgZc+ggAIcNp Z/DNBdp8HsQsJCqZ6jfyltvSNISRmRPPu7yn5/5TRHDEKMuE3AumG11wjWJLIqBCx21v4UrOptWXB OelphXHQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uwdfs-0000000290g-1gE9; Thu, 11 Sep 2025 09:33:04 +0000 Received: from s3.sipsolutions.net ([2a01:4f8:242:246e::2] helo=sipsolutions.net) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1uwdfq-000000028ys-02NP for linux-um@lists.infradead.org; Thu, 11 Sep 2025 09:33:03 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sipsolutions.net; s=mail; h=MIME-Version:Content-Transfer-Encoding: Content-Type:References:In-Reply-To:Date:Cc:To:From:Subject:Message-ID:Sender :Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From:Resent-To: Resent-Cc:Resent-Message-ID; bh=6zJl6jcafeCZ6YmJZKiwF1mOHdjn2LFeup/aII/uTkE=; t=1757583181; x=1758792781; b=k/BNtu8IS74iKhRNOlJDL+9uuOt/OI9pDfYKk3/ipcnYHnq mP1XyAfYSbBtuesg6HTH5HGtQ4mi3LIRsREMv125GQQGg76Gd+/jJsVBu88zUCxyfbIpJADbMRlyz 6WQaUDxE8ZcLo6bv7BBrs1o6L7LbPZN+1R1psnEtz+lyTN5Cv5yLu3wtgbsb99dGVIQcTLoWX9+L1 ijYCusyYQJF3Nzsc3wBq6CLbkJZ2XOxTO1XmghE40qkf39mGZdu10qt5b1xHVaONs0V8r5UTvmh0n lUrNkXhdrYb5uxnF3J7nhIG5rmzkjmWEbf3bjHFg1AachyZyDoQq30dPZp1BWCbQ==; Received: by sipsolutions.net with esmtpsa (TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.98.2) (envelope-from ) id 1uwdfk-0000000F14S-3HyQ; Thu, 11 Sep 2025 11:32:57 +0200 Message-ID: <03cb4661a6135a641c5a3779f2cb424356b8e345.camel@sipsolutions.net> Subject: Re: [PATCH v2 08/10] um: Add initial SMP support From: Johannes Berg To: Tiwei Bie , richard@nod.at, anton.ivanov@cambridgegreys.com Cc: linux-um@lists.infradead.org, linux-kernel@vger.kernel.org, benjamin@sipsolutions.net, arnd@arndb.de, tiwei.btw@antgroup.com Date: Thu, 11 Sep 2025 11:32:56 +0200 In-Reply-To: <20250810055136.897712-9-tiwei.bie@linux.dev> (sfid-20250810_075311_619208_642A3A1A) References: <20250810055136.897712-1-tiwei.bie@linux.dev> <20250810055136.897712-9-tiwei.bie@linux.dev> (sfid-20250810_075311_619208_642A3A1A) Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.56.2 (3.56.2-2.fc42) MIME-Version: 1.0 X-malware-bazaar: not-scanned X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250911_023302_048228_8A8D853C X-CRM114-Status: GOOD ( 10.86 ) X-BeenThere: linux-um@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-um" Errors-To: linux-um-bounces+linux-um=archiver.kernel.org@lists.infradead.org On Sun, 2025-08-10 at 13:51 +0800, Tiwei Bie wrote: > From: Tiwei Bie >=20 > Add initial symmetric multi-processing (SMP) support to UML. With > this support enabled, users can tell UML to start multiple virtual > processors, each represented as a separate host thread. >=20 > In UML, kthreads and normal threads (when running in kernel mode) > can be scheduled and executed simultaneously on different virtual > processors. However, the userspace code of normal threads still > runs within their respective single-threaded stubs. >=20 > That is, SMP support is currently available both within the kernel > and across different processes, but still remains limited within > threads of the same process in userspace. Another thing that isn't covered is anything relating to interrupt affinity, I guess? Is that automatically not working, or will it look like you can change things but that not do anything? I don't think it's important now (though eventually I would actually like to have it for our simulations), but was just thinking about it. johannes