From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sipsolutions.net (s3.sipsolutions.net [168.119.38.16]) (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 C65AF2EA147 for ; Thu, 11 Sep 2025 09:33:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=168.119.38.16 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757583184; cv=none; b=eXorWsdDB9vbFHerPFZ8A/5XJm1cc7l9wE/Ei+3iVNbWtnGqoMVaVdC8PbnHpQHw7XFCq010yzYAD7V8JiT0JsinRrqmr1rRHQhEld203ejN4w+vg80sWjlU3j6jjbrp+yxhsK6bK5YS+I9+OQr13K9SYUAn2tCyXDvjwpLACqI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757583184; c=relaxed/simple; bh=6zJl6jcafeCZ6YmJZKiwF1mOHdjn2LFeup/aII/uTkE=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=dDj67kfXULRKQq8B+pMHztfJNPgSb6irUNaQgMZmzgmz72ENmSR7z7PM+sP3Tf8wI0ztcDiS39UHFXp/LhE1xiEepJDbIElj6O43v2BbA1DA8PYqGFZz66PFlpJ4+ket3xBtW92C+Hg5jsjfrsdC3Ke5lKKvDimgMxh0gM4THks= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sipsolutions.net; spf=pass smtp.mailfrom=sipsolutions.net; dkim=pass (2048-bit key) header.d=sipsolutions.net header.i=@sipsolutions.net header.b=QC+t+69u; arc=none smtp.client-ip=168.119.38.16 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sipsolutions.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=sipsolutions.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=sipsolutions.net header.i=@sipsolutions.net header.b="QC+t+69u" 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=1757583182; x=1758792782; b=QC+t+69uG4DucNnuK/YfvucwvFZUNe4Gccx1wH0hgKL6Zi2 ch4Qkl16qFgxchDiDpaYI7UMsH1JZ5+ZdzHLvw7mw1jgImQUZXBfrMGlCQHE5ectmDaPdDrT6Yu8G cCFmhKKXNFa/y76hX5uwgQn+PV2ytjQ2Buv4RdiDHurx0LTSZp3+If/1V84FVNFVM8aS+g94yYp9R xXq2iCHfw5HfsKtsBYzy1PVXh0Tq/9WSBULDfxRjhmCTM2lv9H19BP35QOXTzwIEKB1XPaAKqAdKg vKHke2r2WJVT326aBvybWXFNdHv3sCLdzY9sFbUz5hk873zVWHC7clFuZecWbDhA==; 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) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-malware-bazaar: not-scanned 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