From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from out30-132.freemail.mail.aliyun.com ([115.124.30.132]:45362 "EHLO out30-132.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726742AbfKKCoc (ORCPT ); Sun, 10 Nov 2019 21:44:32 -0500 Subject: Re: [RFC PATCH 0/4] Speed booting by sorting ORC unwind tables at build time References: <20191107143205.206606-1-shile.zhang@linux.alibaba.com> <20191107152244.GD4114@hirez.programming.kicks-ass.net> <85abe498-f241-4752-81b5-6c0314f5a1e8@linux.alibaba.com> <20191108092136.GH4114@hirez.programming.kicks-ass.net> <20191108092533.GN5671@hirez.programming.kicks-ass.net> From: Shile Zhang Message-ID: <2906cc91-113a-c132-1aef-ba94db31f847@linux.alibaba.com> Date: Mon, 11 Nov 2019 10:44:29 +0800 MIME-Version: 1.0 In-Reply-To: <20191108092533.GN5671@hirez.programming.kicks-ass.net> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-kbuild-owner@vger.kernel.org List-ID: To: Peter Zijlstra Cc: Masahiro Yamada , Michal Marek , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Josh Poimboeuf , x86@kernel.org, "H . Peter Anvin" , linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org On 2019/11/8 17:25, Peter Zijlstra wrote: > On Fri, Nov 08, 2019 at 10:21:36AM +0100, Peter Zijlstra wrote: >> On Fri, Nov 08, 2019 at 09:42:55AM +0800, Shile Zhang wrote: >> >>>> Can sort{ex,orc}table() be ran concurrently? Do they want to be the same >>>> (threaded) tool? >>> I think it is possible to do those sort work concurrently, likes deferred >>> memory init which is big boot time speed up. >>> But I don't know if the exception table and ORC unwind tables can be >>> deferred, due to those tables might be used in early boot time, for early >>> exception handling and early debugging. I'm not familiar with that. >> I meant at link time, run both sorts concurrently such that we only have >> to wait for the longest, instead of the sum of them. >> >> They're not changing the same part of the ELF file, so it should be >> possible to have one tool have multiple threads, each sorting a >> different table. >> >> Aside from the .ex_table and ORC there's also .jump_table that wants >> sorting (see jump_label_sort_entries()). > Oh, and I'll be adding .static_call_sites soon, see: > > https://lkml.kernel.org/r/20191007082708.013939311@infradead.org > > (I should repost that) > > That gives us 4 tables to sort which we can do concurrently in 4 > threads. I got your point now. I'll try to rework the sort tool to sort all tables concurrently in one tool with multiple-threads. Thanks for your advice! >> I agree that doing it at link time makes sense, I just hate to do all >> this sorting in sequence and blowing up the link time. I don't build for >> customers, I build for single use boot and linking _SUCKS_.