From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id 34634A0C47 for ; Tue, 10 Aug 2021 17:41:09 +0200 (CEST) Received: from [217.70.189.124] (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 2F69E411C5; Tue, 10 Aug 2021 17:41:09 +0200 (CEST) Received: from smtp-relay-canonical-1.canonical.com (smtp-relay-canonical-1.canonical.com [185.125.188.121]) by mails.dpdk.org (Postfix) with ESMTP id 72CA44014F for ; Tue, 10 Aug 2021 17:41:07 +0200 (CEST) Received: from mail-ej1-f70.google.com (mail-ej1-f70.google.com [209.85.218.70]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by smtp-relay-canonical-1.canonical.com (Postfix) with ESMTPS id 5B5C33F0B8 for ; Tue, 10 Aug 2021 15:41:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=canonical.com; s=20210705; t=1628610067; bh=GrMWeabeKfZKphO9WDfjniK0gju8Q+/HNDrbhryfkMI=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=gb1Ps1LLZHGDJ7/ZIwhXWIGSSFQsCZlSBjy8ahDhx8xhi21yGIUAf2OCjR2C74tS8 zTIkoL1JI8iDlrbEQwC58ar0sDvUUm7RTIKDDuQ6ZXq1/+v1bFTn+xkuKdXwkxazPb jBvLIdENJl2M4D8CQTeCkbrY+Wqw/9/t1eC8LPE1Nm2QO3WLdfhnZsBZbJz0zHRM5i QJTETr2BEskUGPmXcJy5O2/GIow3Wr896YgHzMOpO5Q8EE9iPPdfIEcZ2NlyTWMbMi DzU4Y+UcmDZLkYoroiEH3njecLX4XuKKxzy+ACbPANamSDV+IPNa9t6FbBtala9jj+ 8j+HCxTih4m1A== Received: by mail-ej1-f70.google.com with SMTP id h17-20020a1709070b11b02905b5ced62193so708139ejl.1 for ; Tue, 10 Aug 2021 08:41:07 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=GrMWeabeKfZKphO9WDfjniK0gju8Q+/HNDrbhryfkMI=; b=KdPUTTAeYpkNsvMGXAp5QTPrxgk94TDiOjkPRE0DeB+XhP9YvvVHik/s0a6UTBJ1CG HUREEq55rBYWr1xtX7wxeqwBmuQ0JdPMZfUSZiTz4L/BpCSRkwdY/OpYegLBCFonIvkF GwAViOSRN0E71h0gHJUJguAI12gtePQNK6dykrN0RCvqu3lYmJ9xnD5i6+Cegb49Z2yu TR0IgDmn8BvC8ldoCTfMppYzWzO6xwdkmRLxjNv3cc80Vq/a2jo7jZgwBVDWSzXt4s3q Gj4Z1Lh8aTT9iKd0N4B2pJRHZkRRSRadUJ/TB9pvRKMXXe1kCh0HqoSmwb1wwh1vEMLm ciiQ== X-Gm-Message-State: AOAM531GaXky/+eVcQYycD7AeStcxgj18RUHfA6TX8PeiQbDPIBd1X+N RSd2RBcM0UXVWPbd1GhxcnCCEsIX0KRZly0DTfxeBX4poTl8zd09slaY8dzZKQ3I27AvvaQ4f5C +7S2MPXm3zxD5Sa33eJxrqzcU X-Received: by 2002:a17:906:fcd7:: with SMTP id qx23mr14829752ejb.267.1628610066791; Tue, 10 Aug 2021 08:41:06 -0700 (PDT) X-Google-Smtp-Source: ABdhPJwagRXd79WvMKHhYBEiSxLAlWQrLshGt+kYzarcLDd/nWHOJRq7ieaVtdlTspA/ovoCzKgemg== X-Received: by 2002:a17:906:fcd7:: with SMTP id qx23mr14829725ejb.267.1628610066556; Tue, 10 Aug 2021 08:41:06 -0700 (PDT) Received: from Keschdeichel.fritz.box ([2001:67c:1560:8007::aac:c4ad]) by smtp.gmail.com with ESMTPSA id r19sm2113142edd.49.2021.08.10.08.41.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Aug 2021 08:41:06 -0700 (PDT) From: christian.ehrhardt@canonical.com To: Ajit Khaparde Cc: dpdk stable Date: Tue, 10 Aug 2021 17:38:52 +0200 Message-Id: <20210810154022.749358-12-christian.ehrhardt@canonical.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210810154022.749358-1-christian.ehrhardt@canonical.com> References: <20210810154022.749358-1-christian.ehrhardt@canonical.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Subject: [dpdk-stable] patch 'doc: fix default burst size in testpmd' has been queued to stable release 19.11.10 X-BeenThere: stable@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: patches for DPDK stable branches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: stable-bounces@dpdk.org Sender: "stable" Hi, FYI, your patch has been queued to stable release 19.11.10 Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable yet. It will be pushed if I get no objections before 08/12/21. So please shout if anyone has objections. Also note that after the patch there's a diff of the upstream commit vs the patch applied to the branch. This will indicate if there was any rebasing needed to apply to the stable branch. If there were code changes for rebasing (ie: not only metadata diffs), please double check that the rebase was correctly done. Queued patches are on a temporary branch at: https://github.com/cpaelzer/dpdk-stable-queue This queued commit can be viewed at: https://github.com/cpaelzer/dpdk-stable-queue/commit/848d502d037115255a7737a96343615c38b67f46 Thanks. Christian Ehrhardt --- >From 848d502d037115255a7737a96343615c38b67f46 Mon Sep 17 00:00:00 2001 From: Ajit Khaparde Date: Fri, 28 May 2021 10:45:29 -0700 Subject: [PATCH] doc: fix default burst size in testpmd [ upstream commit 478614ee1f62e172c4d4770f157fc9bbb6563523 ] Default burst size in testpmd has been changed from 16 to 32 for some time now. But the documentation had not been updated. Fixes: 836853d3d4cf7 ("app/testpmd: increase default burst size to 32") Signed-off-by: Ajit Khaparde --- doc/guides/prog_guide/writing_efficient_code.rst | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/doc/guides/prog_guide/writing_efficient_code.rst b/doc/guides/prog_guide/writing_efficient_code.rst index 849f63efe7..88e6bde047 100644 --- a/doc/guides/prog_guide/writing_efficient_code.rst +++ b/doc/guides/prog_guide/writing_efficient_code.rst @@ -143,20 +143,21 @@ In order to achieve higher throughput, the DPDK attempts to aggregate the cost of processing each packet individually by processing packets in bursts. Using the testpmd application as an example, -the burst size can be set on the command line to a value of 16 (also the default value). -This allows the application to request 16 packets at a time from the PMD. +the burst size can be set on the command line to a value of 32 (also the default value). +This allows the application to request 32 packets at a time from the PMD. The testpmd application then immediately attempts to transmit all the packets that were received, -in this case, all 16 packets. +in this case, all 32 packets. The packets are not transmitted until the tail pointer is updated on the corresponding TX queue of the network port. This behavior is desirable when tuning for high throughput because -the cost of tail pointer updates to both the RX and TX queues can be spread across 16 packets, +the cost of tail pointer updates to both the RX and TX queues can be spread +across 32 packets, effectively hiding the relatively slow MMIO cost of writing to the PCIe* device. However, this is not very desirable when tuning for low latency because -the first packet that was received must also wait for another 15 packets to be received. -It cannot be transmitted until the other 15 packets have also been processed because +the first packet that was received must also wait for another 31 packets to be received. +It cannot be transmitted until the other 31 packets have also been processed because the NIC will not know to transmit the packets until the TX tail pointer has been updated, -which is not done until all 16 packets have been processed for transmission. +which is not done until all 32 packets have been processed for transmission. To consistently achieve low latency, even under heavy system load, the application developer should avoid processing packets in bunches. -- 2.32.0 --- Diff of the applied patch vs upstream commit (please double-check if non-empty: --- --- - 2021-08-10 15:11:13.550661632 +0200 +++ 0012-doc-fix-default-burst-size-in-testpmd.patch 2021-08-10 15:11:12.914637350 +0200 @@ -1 +1 @@ -From 478614ee1f62e172c4d4770f157fc9bbb6563523 Mon Sep 17 00:00:00 2001 +From 848d502d037115255a7737a96343615c38b67f46 Mon Sep 17 00:00:00 2001 @@ -5,0 +6,2 @@ +[ upstream commit 478614ee1f62e172c4d4770f157fc9bbb6563523 ] + @@ -10 +11,0 @@ -Cc: stable@dpdk.org @@ -18 +19 @@ -index 7baeaae431..a61e8320ae 100644 +index 849f63efe7..88e6bde047 100644