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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id EAC91C7EE37 for ; Tue, 6 Jun 2023 22:07:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239829AbjFFWHV (ORCPT ); Tue, 6 Jun 2023 18:07:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52838 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233644AbjFFWHS (ORCPT ); Tue, 6 Jun 2023 18:07:18 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 71F10170C for ; Tue, 6 Jun 2023 15:07:17 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 091C662DA3 for ; Tue, 6 Jun 2023 22:07:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CD255C433D2; Tue, 6 Jun 2023 22:07:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1686089236; bh=EhsLPDAwMF6B/StlX4CuZ4dgWiqs9O/C+kIYo2IjFcs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=OwMRn7f9jCqEFusXNZKX+DuYyjs3WCl+kfFw9hGEVmB44r84tCsaTjL42zairsJHC IULjHEda0Xe8cbHq0fvpxINFoWxyzAF3clOTOpXELGXOY38Z8T1snrZimnYkPQBUYX ftA5AKLdIE42n3P2R3zdh5HhyZNrqZAje6zfWlO+akqi8rDGdfg/sM/2phe2YEBpQW 5keEkYltf0b5NwJn/NTDyJVvs9Ut/+et4CW69yW8qYYL3cjkzg9WNttJgRBIwMwFMV OSuEy7/nmn/8p0BPnG1sAolfYp2SPj/4Dstp087VcKIbfI0A663AJpOv23eGc3Rzb/ lezZz0bvl3f4g== Date: Wed, 7 Jun 2023 00:07:13 +0200 From: Frederic Weisbecker To: Peter Zijlstra Cc: "bibo, mao" , Thomas Gleixner , Huacai Chen , WANG Xuerui , "Rafael J. Wysocki" , Anna-Maria Behnsen , LKML Subject: Re: Loongson (and other $ARCHs?) idle VS timer enqueue Message-ID: References: <87leil2r7v.ffs@tglx> <20230422081700.GB1214746@hirez.programming.kicks-ass.net> <20230422150409.GL1214746@hirez.programming.kicks-ass.net> <7d91fa2a-57c5-6c78-8e2d-7fbdd6a11cba@loongson.cn> <20230425114937.GC1335080@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230425114937.GC1335080@hirez.programming.kicks-ass.net> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 25, 2023 at 01:49:37PM +0200, Peter Zijlstra wrote: > Would not something like the below be a more compact form? > That is; afaict there is no reason to keep it 32 bytes, we can easily go > 16 and drop 4 nops. > > Additionally, instead of truncating to the start, increase to the end by > doing: > > ip |= 0xf; > ip++; > > Also; I added a wee comment. > > > diff --git a/arch/loongarch/kernel/genex.S b/arch/loongarch/kernel/genex.S > index 44ff1ff64260..3c8a6bab98fe 100644 > --- a/arch/loongarch/kernel/genex.S > +++ b/arch/loongarch/kernel/genex.S > @@ -18,27 +18,31 @@ > > .align 5 > SYM_FUNC_START(__arch_cpu_idle) > - /* start of rollback region */ > - LONG_L t0, tp, TI_FLAGS > - nop > - andi t0, t0, _TIF_NEED_RESCHED > - bnez t0, 1f > - nop > - nop > - nop > + /* start of idle interrupt region */ > + move t0, CSR_CRMD_IE > + csrxchg t0, t0, LOONGARCH_CSR_CRMD > + /* > + * If an interrupt lands here; between enabling interrupts above and > + * going idle on the next instruction, we must *NOT* go idle since the > + * interrupt could have set TIF_NEED_RESCHED or caused an timer to need > + * reprogramming. Fall through -- see handle_vint() below -- and have > + * the idle loop take care of things. > + */ > idle 0 > - /* end of rollback region */ > -1: jr ra > + nop > + /* end of idle interrupt region */ > +SYM_INNER_LBEL(__arch_cpu_idle_exit, SYM_L_LOCAL) > + jr ra > SYM_FUNC_END(__arch_cpu_idle) > > SYM_FUNC_START(handle_vint) > BACKUP_T0T1 > SAVE_ALL > - la_abs t1, __arch_cpu_idle > + la_abs t1, __arch_cpu_idle_exit > LONG_L t0, sp, PT_ERA > - /* 32 byte rollback region */ > - ori t0, t0, 0x1f > - xori t0, t0, 0x1f > + /* 16 byte idle interrupt region */ > + ori t0, t0, 0x0f > + addi.d t0, t0, 1 > bne t0, t1, 1f > LONG_S t0, sp, PT_ERA > 1: move a0, sp > diff --git a/arch/loongarch/kernel/idle.c b/arch/loongarch/kernel/idle.c > index 0b5dd2faeb90..5ba72d229920 100644 > --- a/arch/loongarch/kernel/idle.c > +++ b/arch/loongarch/kernel/idle.c > @@ -11,7 +11,6 @@ > > void __cpuidle arch_cpu_idle(void) > { > - raw_local_irq_enable(); > __arch_cpu_idle(); /* idle instruction needs irq enabled */ > raw_local_irq_disable(); > } What is the status of this? Is someone from loongarch going to take it? Thanks.