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 25309C87FCE for ; Mon, 28 Jul 2025 17:11:43 +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:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=UYNcGeys+8gkTrQ2K5DvrFz3i9bs95O5h5mTnWGNU7U=; b=FlRfoI8dEI84FW1EnQnXYHZfr3 kTo6bmFDnq7Q2VDWJfLuMXx7X326enO2Nm+r1sTGaVGxdWPbd4f41rjizZTkayIJApuL864lm/883 om5OsYCC1IxbP/bySixMC6nqmTXOWJ8IUkHNuGThIoaY/bBjGjSwVRc/btftdLfOcd23SVQa+k0J4 yrV681j2SSxDPQC5CSFCgU8hIXXXNBFk+2J1mwhYTghkWTHEG7IR9tgt8feAQbnjro1bl8jFUmQjO enlyiGvvCE5TiN/xMVGhy5HA4MewB3dwatrtSbzCm2+mKEYFlgjL48n6S7ZqEPnaoqP8IaKYL15Sk Z7drClYQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1ugRO2-0000000F4fN-2BnX; Mon, 28 Jul 2025 17:11:42 +0000 Received: from out-174.mta1.migadu.com ([95.215.58.174]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1ugQNc-0000000EvpN-0zjZ for linux-um@lists.infradead.org; Mon, 28 Jul 2025 16:07:13 +0000 X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1753718830; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=UYNcGeys+8gkTrQ2K5DvrFz3i9bs95O5h5mTnWGNU7U=; b=WO1prYN4dOdDgEQd6r7MPRM9udUphzM5z92Ga2WKG7zCS8NpJDa/0KUmVb0hvMXyoydNOG 1l5/k3M6BeddWOPSMWAOFi6mkGae3FCFESDIoc8gkals3rYSxPz8mLw5S64eKF0DkNSgqV kitp2FKGoQJQ5fS7qaojKzL5VRuJLh0= From: Tiwei Bie To: johannes@sipsolutions.net Cc: richard@nod.at, anton.ivanov@cambridgegreys.com, linux-um@lists.infradead.org, tiwei.btw@antgroup.com, tiwei.bie@linux.dev Subject: Re: [PATCH 9/9] um: Add initial SMP support Date: Tue, 29 Jul 2025 00:06:51 +0800 Message-Id: <20250728160651.3268677-1-tiwei.bie@linux.dev> In-Reply-To: <80979dce038d684495b77d6a90d19df7a4b94b9c.camel@sipsolutions.net> References: <80979dce038d684495b77d6a90d19df7a4b94b9c.camel@sipsolutions.net> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250728_090712_416608_7AA04806 X-CRM114-Status: UNSURE ( 9.34 ) X-CRM114-Notice: Please train this message. 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 Mon, 28 Jul 2025 15:55:28 +0200, Johannes Berg wrote: > On Sun, 2025-07-27 at 14:29 +0800, Tiwei Bie wrote: > > > > +static void IPI_handler(int cpu, struct uml_pt_regs *regs) > > +{ > > + struct pt_regs *old_regs = set_irq_regs((struct pt_regs *)regs); > > + unsigned char c; > > + int fd; > > + > > + irq_enter(); > > + > > + if (current->mm) > > + os_alarm_process(current->mm->context.id.pid); > > + > > + fd = uml_cpu_data[cpu].ipi_pipe[0]; > > + while (os_read_file(fd, &c, 1) == 1) { > > We were discussing the IPI stuff and started thinking maybe an RT signal > with sigqueue() passing the value to the si_value in SA_SIGINFO data > would be possible and have less overhead? That way there's nothing on > the SIGIO path, and you don't need a read() for the type of IPI? I like this idea. I will give it a try. Thanks! Regards, Tiwei