From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from eggs.gnu.org (eggs.gnu.org [IPv6:2001:470:142:3::10]) by sourceware.org (Postfix) with ESMTPS id 853193858D1E for ; Mon, 24 Apr 2023 20:47:19 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 853193858D1E Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=gnu.org Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=gnu.org Received: from fencepost.gnu.org ([2001:470:142:3::e]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pr35h-0002mX-EV; Mon, 24 Apr 2023 16:47:18 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=gnu.org; s=fencepost-gnu-org; h=In-Reply-To:MIME-Version:References:Subject:To:From: Date; bh=/0JPbZYuLhB9rRCmB7faluob3XGmLUKa1mKbwJRFUlA=; b=oCHmdzvcL0lLn5hFslwE RMxwko+F6O9eFKCdzIIZj/qLOEHmlDPapnQrXIYWk7V93GqSj8Q7GGrlcWlGP0E9yY3uChwvqih99 rjWaFbtkNyBDwfC7/WvB/tkCp/MixAhw6dQ6hvHm8YUcm3L1HzZkj9kzWpREmnP4o5vLqcrsbt/1N WCrfRssuYmMVtWjyeDf6rkdnPylLnzOBy/5J6ApEXEM37aKW0MI/WSXkg5/KAp9J/9f/e+5Uat3XT PTIJpCBTnBCCJilDjjCIWzXOr1U2CIp5ryCHqzpsRYiXvwfENnyF8xkxzcUmbezIAn3qYwHgEZ8KK SbXnB2qRZb8nrA==; Received: from [2a01:cb19:4a:a400:de41:a9ff:fe47:ec49] (helo=begin.home) by fencepost.gnu.org with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pr35K-0003VE-48; Mon, 24 Apr 2023 16:47:05 -0400 Received: from samy by begin.home with local (Exim 4.96) (envelope-from ) id 1pr35A-003twz-1X; Mon, 24 Apr 2023 22:46:44 +0200 Date: Mon, 24 Apr 2023 22:46:44 +0200 From: Samuel Thibault To: Sergey Bugaev Cc: libc-alpha@sourceware.org, bug-hurd@gnu.org Subject: Re: [PATCH 3/4] hurd: Microoptimize mmap () Message-ID: <20230424204644.omudvkhihy3nzj7m@begin> Mail-Followup-To: Sergey Bugaev , libc-alpha@sourceware.org, bug-hurd@gnu.org References: <20230423215526.346009-1-bugaevc@gmail.com> <20230423215526.346009-3-bugaevc@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230423215526.346009-3-bugaevc@gmail.com> Organization: I am not organized User-Agent: NeoMutt/20170609 (1.8.3) X-Spam-Status: No, score=-12.2 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,GIT_PATCH_0,SPF_HELO_PASS,SPF_PASS,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: Hello, Is it really worth making the code a bit obscure? The mapping RPC will be way more expensive than branch misprediction... Samuel Sergey Bugaev, le lun. 24 avril 2023 00:55:25 +0300, a ecrit: > Signed-off-by: Sergey Bugaev > --- > sysdeps/mach/hurd/mmap.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/sysdeps/mach/hurd/mmap.c b/sysdeps/mach/hurd/mmap.c > index 790eb238..d570be24 100644 > --- a/sysdeps/mach/hurd/mmap.c > +++ b/sysdeps/mach/hurd/mmap.c > @@ -42,7 +42,8 @@ __mmap (void *addr, size_t len, int prot, int flags, int fd, off_t offset) > mapaddr = (vm_address_t) addr; > > /* ADDR and OFFSET must be page-aligned. */ > - if ((mapaddr & (__vm_page_size - 1)) || (offset & (__vm_page_size - 1))) > + if (__glibc_unlikely ((mapaddr & (__vm_page_size - 1)) > + || (offset & (__vm_page_size - 1)))) > return (void *) (long int) __hurd_fail (EINVAL); > > vmprot = VM_PROT_NONE; > @@ -73,7 +74,8 @@ __mmap (void *addr, size_t len, int prot, int flags, int fd, off_t offset) > mach_port_t robj, wobj; > if (err = HURD_DPORT_USE (fd, __io_map (port, &robj, &wobj))) > { > - if (err == MIG_BAD_ID || err == EOPNOTSUPP || err == ENOSYS) > + if (__glibc_unlikely (err == MIG_BAD_ID || err == EOPNOTSUPP > + || err == ENOSYS)) > err = ENODEV; /* File descriptor doesn't support mmap. */ > return (void *) (long int) __hurd_dfail (fd, err); > } > @@ -173,7 +175,7 @@ __mmap (void *addr, size_t len, int prot, int flags, int fd, off_t offset) > if (err == KERN_PROTECTION_FAILURE) > err = EACCES; > > - if (err) > + if (__glibc_unlikely (err)) > return (void *) (long int) __hurd_fail (err); > > return (void *) mapaddr; > -- > 2.40.0