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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (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 4C2C4D637CF for ; Thu, 14 Nov 2024 02:01:35 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [127.0.0.1]) by lists.ozlabs.org (Postfix) with ESMTP id 4Xpk0Y5Q4Hz2yFQ; Thu, 14 Nov 2024 13:01:33 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; arc=none smtp.remote-ip=150.107.74.76 ARC-Seal: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1731549693; cv=none; b=DCN+OucdnPIQquYL9h44VcCLR9t2EJfLGcAqtvs3+Z+smSU+hKqAb1FpljUjGH1pLAGtR0t3SF5rUgMTtuOE7UV4k3PrcAr7rBUiBj+ktTqsLsiu4i2P3XqmH7osPr7DmIhUUb2NCKxLv7IkDhE8czwQysL/QqY1aYSb6clxPB5SLcC6Usj+XeCSHPEvNEjbkGMZzARQR9p5EXdcALkwoRT7BnBvzyxQLzDb9okRHBcjt7mfs1MWQ2A9lfbQYA2s/wxJYr6U7VTpETxIHPueNw63R4sVUc3pzcBoFP2zDRxdWbuv5lFkuozDLL/NetFi/Zmcw9H6z5s9BjBvDFUb9w== ARC-Message-Signature: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1731549693; c=relaxed/relaxed; bh=VgxfHan4ibP4AC8pjrjxkAg6/1BZbxzGeV5qGbYQ3ns=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=UGPtOXaxstEZvj7D7zpmFua6e6R3PWqtcAoxYbWsuSVN8hhz05sK47S6lVIYiL7oOUC9HsyRCpWfliM78Wwshts4imzVc6NSx3tvLsyxzExXsIGBQ7SU3YOx3ryFUkrRGt71yoeCGRwbGL5YSL0rmZ/dsN/aFkrPFbakhCr3vyJCLEfvdPABgfxigg4qiGtYHkG3JAizyUl6pTiaFaTBXqxDqrS1wPfYgeWcecIMJ+gt0sXy2MV8jXbTmZuY7jNUo/JZHlOHLs7fFydMHs5GPUR4la9XoU8a1R21J3KPp85n/J8xcDMPlts0lEYw1FctOOCoVb2nNXxV+YdgPbnRcA== ARC-Authentication-Results: i=1; lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=ellerman.id.au; dkim=pass (2048-bit key; unprotected) header.d=ellerman.id.au header.i=@ellerman.id.au header.a=rsa-sha256 header.s=201909 header.b=T4QAN1bV; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=ellerman.id.au Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=ellerman.id.au header.i=@ellerman.id.au header.a=rsa-sha256 header.s=201909 header.b=T4QAN1bV; dkim-atps=neutral Received: from mail.ozlabs.org (gandalf.ozlabs.org [150.107.74.76]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4Xpk0X4ZhHz2y8d for ; Thu, 14 Nov 2024 13:01:32 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ellerman.id.au; s=201909; t=1731549688; bh=VgxfHan4ibP4AC8pjrjxkAg6/1BZbxzGeV5qGbYQ3ns=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=T4QAN1bVWbsNolhMLF76SleNUY1gmJNDQwjzKD4jkNSO9qmw+WHdubTxlaFuhhoFV GCgM9uTxUaoajIB6MBGeqXdLPHbbWlOvceeToPkJKzlrKjF8WXa1ZeqTmCg/MGwbSt NCudE0lNLXEf7bf4UPAjsG2lgD/6AH5ABQNpymXj8HBu5qRe3MW/lNLKSXctULROfY JqM98BkCaxjpRpeF4kpQtiB83Q1zYwqiKKyUPPWhGAQkVTFwRFj4l1+GyJmgglBAFN X7/V4n/9N7YF+508bgJXng1/G+WXIZzbryaFzoFcFtTRcNKxNK0iA7ckP2/rMQtkPY dTzHmQWtgxoPA== Received: from authenticated.ozlabs.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mail.ozlabs.org (Postfix) with ESMTPSA id 4Xpk0R3p1lz4x7X; Thu, 14 Nov 2024 13:01:27 +1100 (AEDT) From: Michael Ellerman To: Shrikanth Hegde , Sebastian Andrzej Siewior Cc: linuxppc-dev@lists.ozlabs.org, npiggin@gmail.com, maddy@linux.ibm.com, christophe.leroy@csgroup.eu, peterz@infradead.org, ankur.a.arora@oracle.com Subject: Re: [PATCH] powerpc: Add preempt lazy support In-Reply-To: <054a79d6-85a4-4c02-a361-d8e4b34ca674@linux.ibm.com> References: <20241108101853.277808-1-sshegde@linux.ibm.com> <20241108105031.Uq8MV60I@linutronix.de> <054a79d6-85a4-4c02-a361-d8e4b34ca674@linux.ibm.com> Date: Thu, 14 Nov 2024 13:01:29 +1100 Message-ID: <877c96vaiu.fsf@mpe.ellerman.id.au> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain Shrikanth Hegde writes: > Thank you Sebastian for taking a look and rwb tag. > >> On 2024-11-08 15:48:53 [+0530], Shrikanth Hegde wrote: >>> Define preempt lazy bit for Powerpc. Use bit 9 which is free and within >>> 16 bit range of NEED_RESCHED, so compiler can issue single andi. >>> >>> Since Powerpc doesn't use the generic entry/exit, add lazy check at exit >>> to user. CONFIG_PREEMPTION is defined for lazy/full/rt so use it for >>> return to kernel. >>> >>> Ran a few benchmarks and db workload on Power10. Performance is close to >>> preempt=none/voluntary. It is possible that some patterns would >>> differ in lazy[2]. More details of preempt lazy is here [1] >>> >>> Since Powerpc system can have large core count and large memory, >>> preempt lazy is going to be helpful in avoiding soft lockup issues. >>> >>> [1]: https://lore.kernel.org/lkml/20241007074609.447006177@infradead.org/ >>> [2]: https://lore.kernel.org/all/1a973dda-c79e-4d95-935b-e4b93eb077b8@linux.ibm.com/ >> >> The lazy bits are only in tip. > > Hi Michael, I sent it to powerpc tree since all the changes were in > arch/powerpc. Please let me know if i have send it to tip tree instead. I think I'd like it to have a full cycle of testing in next before going into mainline. So I'll plan to take this via the powerpc tree for the next cycle. I assume you haven't tested 32-bit at all? cheers