From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp-out1.suse.de (smtp-out1.suse.de [IPv6:2001:67c:2178:6::1c]) by sourceware.org (Postfix) with ESMTPS id F39533858D33 for ; Thu, 4 May 2023 13:05:23 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org F39533858D33 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: sourceware.org; spf=fail smtp.mailfrom=suse.cz Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id EFB7021DDF; Thu, 4 May 2023 13:05:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1683205522; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ED2w18NgeIxFFP333GR/KKzfN+uouSMYNI0oUJHcyoM=; b=DDecxUN6ox8CnNgjOEXOy5Oa1ycOojaPmwxHSGcweUxjAYxmmwWSQVkoBgWOZGAp76n4N1 sFcWgCAHOUV8LYa8dF6FqSVbxsqKeOi4o+z/PGLsZGyNizycEWLNTx4E9cS6OM4+Mi2L2o u2NC08L+sILeK+TKZ4Nj0w1skiM6BZA= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1683205522; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ED2w18NgeIxFFP333GR/KKzfN+uouSMYNI0oUJHcyoM=; b=lxDPW5zbWIj1fUWdzd4lffG+vvFmBQJQU1VU2lpoxMdmh3ERPyt9P05JPm0vUW1/qZKFW9 8JNDh5b1DAPiXLBQ== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id D5FA713444; Thu, 4 May 2023 13:05:22 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id 97RRM5KtU2QFUgAAMHmgww (envelope-from ); Thu, 04 May 2023 13:05:22 +0000 Message-ID: <83fbeb1d-9bf8-1434-d8cb-a9827b1af266@suse.cz> Date: Thu, 4 May 2023 15:05:22 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.10.1 Subject: Re: Question on patch -fprofile-partial-training Content-Language: en-US To: Qing Zhao Cc: Jan Hubicka , gcc Patches References: <2A707DB2-5BCE-4F1F-A971-67AC55B30297@oracle.com> <5FEEC8EF-85A8-4A94-ABE0-3E783F0C8A7C@oracle.com> From: =?UTF-8?Q?Martin_Li=c5=a1ka?= In-Reply-To: <5FEEC8EF-85A8-4A94-ABE0-3E783F0C8A7C@oracle.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-7.7 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,NICE_REPLY_A,SPF_HELO_NONE,SPF_SOFTFAIL,TXREP,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: On 5/4/23 14:54, Qing Zhao wrote: > > >> On May 4, 2023, at 4:30 AM, Martin Liška wrote: >> >> On 5/3/23 21:10, Qing Zhao via Gcc-patches wrote: >>> Hi, Jan, >>> >>> You added the following patch into gcc10: >>> >>> From 34fbe3f0946f88828765184ed6581bda62cdf49f Mon Sep 17 00:00:00 2001 >>> From: Jan Hubicka >>> Date: Thu, 5 Dec 2019 19:12:51 +0100 >>> Subject: [PATCH] cgraphclones.c (localize_profile): New function. >>> >>> * cgraphclones.c (localize_profile): New function. >>> (cgraph_node::create_clone): Use it for partial profiles. >>> * common.opt (fprofile-partial-training): New flag. >>> * doc/invoke.texi (-fprofile-partial-training): Document. >>> * ipa-cp.c (update_profiling_info): For partial profiles do not >>> set function profile to zero. >>> * profile.c (compute_branch_probabilities): With partial profile >>> watch if edge count is zero and turn all probabilities to guessed. >>> (compute_branch_probabilities): For partial profiles do not apply >>> profile when entry count is zero. >>> * tree-profile.c (tree_profiling): Only do value_profile_transformations >>> when profile is read. >>> >>> My question is: >> >> Hello. >> >> Why would anybody backport such change to unsupported code-stream of GCC 8? >> Generally speaking, I discourage from doing that. > > Yes, I agree. > However, many users still use GCC8 right now, and some of them are asking for more performance > from PGO recently. That’s the reason I am studying this right now. I understand there are products that are based on GCC8, but as the branch is officially unsupported, I don't see a reason to backport a new feature from newer release. It's just asking for troubles. If your clients are interested in more performance, then they should use a recent supported release. > > From my understanding, -fprofile-partial-training is one important option for PGO performance. I don't think so, speed benefit would be rather small I guess. > I’d like > to see any big technique difficult to prevent it from being back ported to GCC8. There might be of course some patch dependencies and I don't see a point why should we waste time with that. Cheers, Martin > > Thanks. > > Qing > >> >> Martin >> >>> >>> Can this patch be back ported to GCC8 easily? I am wondering any significant >>> Change between GCC8 and GCC10 that might make the backporting very hard> >>> Thanks a lot for your help. >>> >>> Qing >