From patchwork Tue Nov 29 21:59:25 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Brown X-Patchwork-Id: 630057 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 77D8FC46467 for ; Tue, 29 Nov 2022 22:00:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234423AbiK2WAK (ORCPT ); Tue, 29 Nov 2022 17:00:10 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41190 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236192AbiK2V7l (ORCPT ); Tue, 29 Nov 2022 16:59:41 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3DC8C6F0EB for ; Tue, 29 Nov 2022 13:59:40 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id DCFE5B81982 for ; Tue, 29 Nov 2022 21:59:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 33A31C433D6; Tue, 29 Nov 2022 21:59:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1669759177; bh=ljBbwXbpFXylIv5/T0HUheeXkTvpejFf0PIQp2UDE54=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=XjqEg0MFHoe2NRdlYELnD55gyH5YlG+KHhReuPjnTS1om0cBDp4S6rCedAkYY0Fjz D0NaesqX4kUbJqfyyVlaQUx/zyuxS4C8HnhyqWn9+sn5/WjeuNldmKrc7a87FWwkCQ eR1wnAIBht6423NP2cX6NT0ELUvA62wk0Ynw2pDilkoyOdKDUKRr+VzDs1rBOtAZr/ q9xz2Ai7hV3Z7D3znA0CXK6f0+7JjYvQe7uBjk4BnKRRylXxX8X1wRv5RW+u5ouKH/ YiLLwnrsIIh/XLz/49oRG5SpVnHEW0TZPyZ4pn+ps899IhsicpV1TH/yfBR3+jdI7p dVI9oqSHwhMqA== From: Mark Brown To: Catalin Marinas , Will Deacon , Shuah Khan Cc: linux-arm-kernel@lists.infradead.org, linux-kselftest@vger.kernel.org, Mark Brown Subject: [PATCH v2 3/3] kselftest/arm64: Allow epoll_wait() to return more than one result Date: Tue, 29 Nov 2022 21:59:25 +0000 Message-Id: <20221129215926.442895-4-broonie@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20221129215926.442895-1-broonie@kernel.org> References: <20221129215926.442895-1-broonie@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3405; i=broonie@kernel.org; h=from:subject; bh=ljBbwXbpFXylIv5/T0HUheeXkTvpejFf0PIQp2UDE54=; b=owEBbQGS/pANAwAKASTWi3JdVIfQAcsmYgBjhoC9A5hGVU7vrA26t1EofYEAYFWU+d06yuxERowW NHf5mnOJATMEAAEKAB0WIQSt5miqZ1cYtZ/in+ok1otyXVSH0AUCY4aAvQAKCRAk1otyXVSH0HutB/ 9EtlLjCLWE6479Xq7SRHRmkOeZHGiW8VuS2J1o1KWRgT4ApriYUULxzrOrEHfPK4zTlKXngz36MAYt SMp0guIKlf/BbM/ZTtbqSyfkQJcxVT5o0edBS69yO0PIcR4D5OOZTAcJ4fZKuzB2yqp2U+pP6FVk2e gdgquW/u5YIFceUL1ycSd9FdjyaoNpeh5AhlusBjx6SxRHQQ/iHDdtCpvHdv3uWx+VozhwtvqW87eU FMx3zEdfRT/hfXVmCDMyWqrfsRQPV0qaV4PIWUYiQws+eLWWEKhuh4tHQexzOLnNjdNDkpJt5ASrJE Rael97M7oOifNEO8oUT0uaAmNshYBv X-Developer-Key: i=broonie@kernel.org; a=openpgp; fpr=3F2568AAC26998F9E813A1C5C3F436CA30F5D8EB Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org When everything is starting up we are likely to have a lot of child processes producing output at once. This means that we can reduce overhead a bit by allowing epoll_wait() to return more than one descriptor at once, it cuts down on the number of system calls we need to do which on virtual platforms where the syscall overhead is a bit more noticable and we're likely to have a lot more children active can make a small but noticable difference. On physical platforms the relatively small number of processes being run and vastly improved speeds push the effects of this change into the noise. Signed-off-by: Mark Brown --- tools/testing/selftests/arm64/fp/fp-stress.c | 27 +++++++++++++------- 1 file changed, 18 insertions(+), 9 deletions(-) diff --git a/tools/testing/selftests/arm64/fp/fp-stress.c b/tools/testing/selftests/arm64/fp/fp-stress.c index b3bbfe8d9f56..f8b2f41aac36 100644 --- a/tools/testing/selftests/arm64/fp/fp-stress.c +++ b/tools/testing/selftests/arm64/fp/fp-stress.c @@ -39,6 +39,8 @@ struct child_data { static int epoll_fd; static struct child_data *children; +static struct epoll_event *evs; +static int tests; static int num_children; static bool terminate; @@ -393,11 +395,11 @@ static void probe_vls(int vls[], int *vl_count, int set_vl) /* Handle any pending output without blocking */ static void drain_output(bool flush) { - struct epoll_event ev; int ret = 1; + int i; while (ret > 0) { - ret = epoll_wait(epoll_fd, &ev, 1, 0); + ret = epoll_wait(epoll_fd, evs, tests, 0); if (ret < 0) { if (errno == EINTR) continue; @@ -405,8 +407,8 @@ static void drain_output(bool flush) strerror(errno), errno); } - if (ret == 1) - child_output(ev.data.ptr, ev.events, flush); + for (i = 0; i < ret; i++) + child_output(evs[i].data.ptr, evs[i].events, flush); } } @@ -419,12 +421,11 @@ int main(int argc, char **argv) { int ret; int timeout = 10; - int cpus, tests, i, j, c; + int cpus, i, j, c; int sve_vl_count, sme_vl_count, fpsimd_per_cpu; bool all_children_started = false; int seen_children; int sve_vls[MAX_VLS], sme_vls[MAX_VLS]; - struct epoll_event ev; struct sigaction sa; while ((c = getopt_long(argc, argv, "t:", options, NULL)) != -1) { @@ -510,6 +511,11 @@ int main(int argc, char **argv) ksft_print_msg("Failed to install SIGCHLD handler: %s (%d)\n", strerror(errno), errno); + evs = calloc(tests, sizeof(*evs)); + if (!evs) + ksft_exit_fail_msg("Failed to allocated %d epoll events\n", + tests); + for (i = 0; i < cpus; i++) { for (j = 0; j < fpsimd_per_cpu; j++) start_fpsimd(&children[num_children++], i, j); @@ -543,7 +549,7 @@ int main(int argc, char **argv) * useful in emulation where we will both be slow and * likely to have a large set of VLs. */ - ret = epoll_wait(epoll_fd, &ev, 1, 1000); + ret = epoll_wait(epoll_fd, evs, tests, 1000); if (ret < 0) { if (errno == EINTR) continue; @@ -552,8 +558,11 @@ int main(int argc, char **argv) } /* Output? */ - if (ret == 1) { - child_output(ev.data.ptr, ev.events, false); + if (ret > 0) { + for (i = 0; i < ret; i++) { + child_output(evs[i].data.ptr, evs[i].events, + false); + } continue; }