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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 04378C433EF for ; Tue, 9 Nov 2021 01:10:03 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 501F761B51 for ; Tue, 9 Nov 2021 01:10:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 501F761B51 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ellerman.id.au Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.ozlabs.org Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4Hp8zD6Cswz2yp4 for ; Tue, 9 Nov 2021 12:10:00 +1100 (AEDT) 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=fX34aeA5; dkim-atps=neutral Received: from gandalf.ozlabs.org (gandalf.ozlabs.org [IPv6:2404:9400:2:0:216:3eff:fee2:21ea]) (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 4Hp8yY3MzWz2xBk for ; Tue, 9 Nov 2021 12:09:25 +1100 (AEDT) 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=fX34aeA5; dkim-atps=neutral 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 ECDHE (P-256) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mail.ozlabs.org (Postfix) with ESMTPSA id 4Hp8yY29P6z4xfd; Tue, 9 Nov 2021 12:09:25 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ellerman.id.au; s=201909; t=1636420165; bh=ZuGKCBySZKxkZrtRo+DH0Bhlb5cjlbDZLng4fqfchUE=; h=From:To:Subject:In-Reply-To:References:Date:From; b=fX34aeA5oGq4yB1DJJE2xwtfLPHheVWpUDxbSgXy3JS6TFxSgwJsgV3xE/1aG6/5N UmfEDxiWKoTvII4QRaOsAF3a/dq2KK/NxUj81f4YrrTVsjiuuaXk/iUHdPvAE7YOfy nXJ728y8ZPdC7/8y28jBc//SaUU81qEk1pIfoK1gkn58Kb0zmQSL+oQ5e10q4qB05x MlmWHOI363BgjE/6beMXzeK8CFkgUAjNR+2EJapfCLLZA8TyLfrvwASF+hMT313771 JdLkR8CsG3IQ/vA9nXvL0XYRUnmy56QAADIq51pauZVGF7yh8m+URBEFWfwE7MBs75 kOazJOUWsgSSw== From: Michael Ellerman To: Nicholas Piggin , linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH] powerpc/64s: introduce CONFIG_MAXSMP to test very large SMP In-Reply-To: <1636379634.t1oqdo5jl5.astroid@bobo.none> References: <20211105041132.1443767-1-npiggin@gmail.com> <87pmrb6ws6.fsf@mpe.ellerman.id.au> <1636379634.t1oqdo5jl5.astroid@bobo.none> Date: Tue, 09 Nov 2021 12:09:24 +1100 Message-ID: <87v912m8xn.fsf@mpe.ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Nicholas Piggin writes: > Excerpts from Michael Ellerman's message of November 8, 2021 3:28 pm: >> Nicholas Piggin writes: >>> Similarly to x86, add MAXSMP that should help flush out problems with >>> vary large SMP and other values associated with very big systems. >>> >>> Signed-off-by: Nicholas Piggin >>> --- >>> arch/powerpc/Kconfig | 8 ++++++++ >>> arch/powerpc/platforms/Kconfig.cputype | 5 +++-- >>> 2 files changed, 11 insertions(+), 2 deletions(-) >>> >>> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig >>> index b8f6185d3998..d585fcfa456f 100644 >>> --- a/arch/powerpc/Kconfig >>> +++ b/arch/powerpc/Kconfig >>> @@ -64,6 +64,13 @@ config NEED_PER_CPU_EMBED_FIRST_CHUNK >>> config NEED_PER_CPU_PAGE_FIRST_CHUNK >>> def_bool y if PPC64 >>> >>> +config MAXSMP >>> + bool "Enable Maximum number of SMP Processors and NUMA Nodes" >>> + depends on SMP && DEBUG_KERNEL && PPC_BOOK3S_64 >>> + help >>> + Enable maximum number of CPUS and NUMA Nodes for this architecture. >>> + If unsure, say N. >> >> As evidenced by the kernel robot report, I think we need to exclude this >> from allyesconfig. >> >> Because our max is 16K, larger than the 8K on x86, we are going to be >> constantly hitting stack usage errors in driver code. Getting those >> fixed tends to take time, because the driver authors don't see the >> warnings when they build for other arches, and because the fixes go via >> driver trees. > > Yeah I realised after I hit send. Surprisingly there weren't too many > but agree going ahead of x86 would always come with annoyances and at > least would have to fix existing tree. > >> Making MAXSMP depend on !COMPILE_TEST should do the trick. > > I'll do that. Or maybe make it 8192 if COMPILE_TEST otherwise 16384. Yeah that could be OK. > The reason for 16K is if we bump the deault at some point we might go to > 8K, in which case it would be good to have a test above it to catch > marginal cases. Yeah makes sense to have some head room. cheers