From patchwork Tue Dec 7 13:02:04 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Florian Weimer X-Patchwork-Id: 48581 Return-Path: X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id E3F543858414 for ; Tue, 7 Dec 2021 13:03:49 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org E3F543858414 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1638882229; bh=j1pvRRfa1evyn+8AwZnX7gbyVmLH9f0HDF4Jcd3ibJg=; h=To:Subject:In-Reply-To:References:Date:List-Id:List-Unsubscribe: List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To: From; b=Z5zibG5eNN6pXXPGjGGmrAJ5/yvwY/TBFtrnyKYBNadcLoEBIs9bqi2d4mM6Q+q9Y 7E/VFwIWvrQxK88VHtxd6VOE+Lu57ccJsvR8jb923+dZyW2a52hMIIrCbR8aZWkUu6 OjXwzIGx2ck212EOrFIKqIpl7SOv7aUAl4Cz+a6U= X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by sourceware.org (Postfix) with ESMTPS id 13D4C385843D for ; Tue, 7 Dec 2021 13:02:10 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 13D4C385843D Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-17-IcO3Na-HOhKREseYCioD2A-1; Tue, 07 Dec 2021 08:02:08 -0500 X-MC-Unique: IcO3Na-HOhKREseYCioD2A-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 7E07010766D5 for ; Tue, 7 Dec 2021 13:02:07 +0000 (UTC) Received: from oldenburg.str.redhat.com (unknown [10.39.193.123]) by smtp.corp.redhat.com (Postfix) with ESMTPS id EE69D100AE22 for ; Tue, 7 Dec 2021 13:02:06 +0000 (UTC) To: libc-alpha@sourceware.org Subject: [PATCH v2 5/8] Linux: Use rseq to accelerate sched_getcpu In-Reply-To: References: X-From-Line: 450326fdf3964e5539aa2da1b9836d51491f8fdb Mon Sep 17 00:00:00 2001 Message-Id: <450326fdf3964e5539aa2da1b9836d51491f8fdb.1638880889.git.fweimer@redhat.com> Date: Tue, 07 Dec 2021 14:02:04 +0100 User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-Spam-Status: No, score=-12.5 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H3, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_NONE, TXREP autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Florian Weimer via Libc-alpha From: Florian Weimer Reply-To: Florian Weimer Errors-To: libc-alpha-bounces+patchwork=sourceware.org@sourceware.org Sender: "Libc-alpha" Co-Authored-By: Mathieu Desnoyers Reviewed-by: Szabolcs Nagy --- v2: Use volatile access. sysdeps/unix/sysv/linux/sched_getcpu.c | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-) diff --git a/sysdeps/unix/sysv/linux/sched_getcpu.c b/sysdeps/unix/sysv/linux/sched_getcpu.c index c41e986f2c..6f78edaea1 100644 --- a/sysdeps/unix/sysv/linux/sched_getcpu.c +++ b/sysdeps/unix/sysv/linux/sched_getcpu.c @@ -20,8 +20,8 @@ #include #include -int -sched_getcpu (void) +static int +vsyscall_sched_getcpu (void) { unsigned int cpu; int r = -1; @@ -32,3 +32,18 @@ sched_getcpu (void) #endif return r == -1 ? r : cpu; } + +#ifdef RSEQ_SIG +int +sched_getcpu (void) +{ + int cpu_id = THREAD_GETMEM_VOLATILE (THREAD_SELF, rseq_area.cpu_id); + return __glibc_likely (cpu_id >= 0) ? cpu_id : vsyscall_sched_getcpu (); +} +#else /* RSEQ_SIG */ +int +sched_getcpu (void) +{ + return vsyscall_sched_getcpu (); +} +#endif /* RSEQ_SIG */