From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl1-x635.google.com (mail-pl1-x635.google.com [IPv6:2607:f8b0:4864:20::635]) by sourceware.org (Postfix) with ESMTPS id 0B762388A400 for ; Fri, 23 Apr 2021 17:27:14 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 0B762388A400 Received: by mail-pl1-x635.google.com with SMTP id e9so8577516plj.2 for ; Fri, 23 Apr 2021 10:27:14 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=k6hBfaLCUHIOMkJKhfyC+tMP2i2mdpMbRsdbK2mXUK4=; b=CgdpaBh2u+El+15XmopWuKOWVs2/6b0/F/anfPkZlec8mrgy8SsYKF69V1+ZCc4fDR 5cOzbbdvLm7EYm24tdCX89taS54iJRo1NwKvYYJemN0VmJN4IdsD0DjgjoE2omJYZtAQ YNmGESVIBXpOTJOKNEc4VwrAnXMeh5nAkd6vdyAyA60vfV2sOBRGSOOFTHqnqGhtTosW raOEDJexkIB2sgd7T+xz7obn3TXP9qpiLiKGyEAVF0i0fDUHdl8CsHsruAQZbrvicFXv WiW+8f6MckyW876ZKd44WV370bOmDlI7LmkJBVU33D3wsslJUzvbX28O5LY9cMuAbyjl b8LA== X-Gm-Message-State: AOAM530OHN4AAM8Ns23+U62KgOwnmloYkUItw+omPNx+0U5ikuycS6RX j79Vb1eZVwUsOnLCNe08QGJW2IJVTFuYFG22cZjSkQ== X-Google-Smtp-Source: ABdhPJwlDtejLLQ+6ufsx9DmWTwWNYp1Hg07HzPVRMx7OfOhnMAPOX9vwP8f0X6rfCX/o5PczCougdkrRfYEaD5lWlg= X-Received: by 2002:a17:902:eec5:b029:ea:bffe:2b06 with SMTP id h5-20020a170902eec5b02900eabffe2b06mr5245248plb.8.1619198833022; Fri, 23 Apr 2021 10:27:13 -0700 (PDT) MIME-Version: 1.0 References: <62330f82-201d-af7d-d1ed-1c8c529cc0f7@suse.cz> <20210422222906.GB5803@kam.mff.cuni.cz> <20210423165449.GC56452@kam.mff.cuni.cz> <20210423171611.GA82007@kam.mff.cuni.cz> In-Reply-To: <20210423171611.GA82007@kam.mff.cuni.cz> From: Xinliang David Li Date: Fri, 23 Apr 2021 10:27:02 -0700 Message-ID: Subject: Re: State of AutoFDO in GCC To: Jan Hubicka Cc: "gcc@gcc.gnu.org" , Eugene Rozenfeld X-Spam-Status: No, score=-16.2 required=5.0 tests=BAYES_00, DKIMWL_WL_MED, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, ENV_AND_HDR_SPF_MATCH, HTML_MESSAGE, KAM_SHORT, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP, USER_IN_DEF_DKIM_WL, USER_IN_DEF_SPF_WL autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org Content-Type: text/plain; charset="UTF-8" X-Content-Filtered-By: Mailman/MimeDel 2.1.29 X-BeenThere: gcc@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 23 Apr 2021 17:27:16 -0000 On Fri, Apr 23, 2021 at 10:16 AM Jan Hubicka wrote: > > > > It uses create_llvm_prof tool which is in the same git repo. The data > > parsing part is shared with create_gcov, but the writer is obviously > > different for the two tools. > > OK and what are the main differences between llvmand gcc format? > > GCC expects GCOV format, I think while LLVM uses a newly designed binary format. David > Honza > > > > David > > > > > > > Honza > > > > > > > > David > > > > > > > > > > > > > > Thoughts? > > > > > Martin > > > > > > > > > > > > > > > > > Having the tool third-party makes keeping the whole chain working > > > more > > > > > > difficult. > > > > > > > > > > > > Richard. > > > > > > > > > > > >> Thanks, > > > > > >> > > > > > >> David > > > > > >> > > > > > >> On Thu, Apr 22, 2021 at 3:29 PM Jan Hubicka > wrote: > > > > > >> > > > > > >>>> On 4/22/21 9:58 PM, Eugene Rozenfeld via Gcc wrote: > > > > > >>>>> GCC documentation for AutoFDO points to create_gcov tool that > > > > > converts > > > > > >>> perf.data file into gcov format that can be consumed by gcc > with > > > > > >>> -fauto-profile ( > > > > > https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html, > > > > > >>> https://gcc.gnu.org/wiki/AutoFDO/Tutorial). > > > > > >>>>> > > > > > >>>>> I noticed that the source code for create_gcov has been > deleted > > > from > > > > > >>> https://github.com/google/autofdo on April 7. I asked about > that > > > > > change > > > > > >>> in that repo and got the following reply: > > > > > >>>>> > > > > > >>>>> > > > https://github.com/google/autofdo/pull/107#issuecomment-819108738 > > > > > >>>>> > > > > > >>>>> "Actually we didn't use create_gcov and havn't updated > > > create_gcov > > > > > for > > > > > >>> years, and we also didn't have enough tests to guarantee it > works > > > (It > > > > > was > > > > > >>> gcc-4.8 when we used and verified create_gcov). If you need > it, it > > > is > > > > > >>> welcomed to update create_gcov and add it to the respository." > > > > > >>>>> > > > > > >>>>> Does this mean that AutoFDO is currently dead in gcc? > > > > > >>>> > > > > > >>>> Hello. > > > > > >>>> > > > > > >>>> Yes. I know that even basic test cases have been broken for > years > > > in > > > > > the > > > > > >>> GCC. > > > > > >>>> It's new to me that create_gcov was removed. > > > > > >>>> > > > > > >>>> I tend to send patch to GCC that will remove AutoFDO from GCC. > > > > > >>>> I known Bin spent some time working on AutoFDO, has he came > up to > > > > > >>> something? > > > > > >>> > > > > > >>> The GCC side of auto-FDO is not that hard. We have most of > > > > > >>> infrastructure in place, but stopping point for me was always > > > > > difficulty > > > > > >>> to get gcov-tool working. If some maintainer steps up, I > think I > > > can > > > > > >>> fix GCC side. > > > > > >>> > > > > > >>> I am bit unsure how important feature it is - we have FDO that > > > works > > > > > >>> quite well for most users but I know there are some users of > the > > > LLVM > > > > > >>> implementation and there is potential to tie this with other > > > hardware > > > > > >>> events to asist i.e. if conversion (where one wants to know how > > > well > > > > > CPU > > > > > >>> predicts the jump rather than just the jump probability) which > I > > > always > > > > > >>> found potentially interesting. > > > > > >>> > > > > > >>> Honza > > > > > >>>> > > > > > >>>> Martin > > > > > >>>> > > > > > >>>>> > > > > > >>>>> Thanks, > > > > > >>>>> > > > > > >>>>> Eugene > > > > > >>>>> > > > > > >>>> > > > > > >>> > > > > > > > > > > > > > >