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 1A314A0C4C for ; Mon, 12 Jul 2021 15:11:31 +0200 (CEST) Received: from [217.70.189.124] (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 13CED4069D; Mon, 12 Jul 2021 15:11:31 +0200 (CEST) Received: from mail-wr1-f41.google.com (mail-wr1-f41.google.com [209.85.221.41]) by mails.dpdk.org (Postfix) with ESMTP id 1669241177 for ; Mon, 12 Jul 2021 15:11:29 +0200 (CEST) Received: by mail-wr1-f41.google.com with SMTP id f17so25561889wrt.6 for ; Mon, 12 Jul 2021 06:11:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=YAHKqX6CuBemG9zDxLQDON56ZcmOR2hrTrLhgNnBQ4M=; b=u2PPRN2TDAJJ4NyGKUfuTdfpGU+dKSVS9/4z2COovSQ4EXgKBYAbSTDo9bwufCYF4U QBxJTBbQU8rgoql9xo2mFSVTMQQ6429jGotHQQV8mdO4phfkvnHr3yBIpg5K0I49xQuK aZ0C7bvXOZuGRfRuCwaDL9b1rbw2AYqM1X9hheJGmXIQLLvb6rWdV73coCVQrJYOwRNt Yr/lTQxUaJqWpAg1pp07+n0PxHFZXCsNMWNR9Gyx4dGJLPF4Cp1jiIc2tzz63AbXK1+f bHh12Dlc21af//FypKY3MWjh1sl0e1cw6phRzSnjoDWY5A83wM7tZIasOMdIdN1s0zut /moQ== 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=YAHKqX6CuBemG9zDxLQDON56ZcmOR2hrTrLhgNnBQ4M=; b=D49zsw19GT/0pRWZwzJcV4pL2FEUVSSuAlbj/IBj5qMLYqSjdR7b+eqXuw2Wnivi0e m45so9PnwUS2fnRJms9UPjSom1RNtKSdMaV6HkolGPgpszLZ/8fIPoYJrhE7+vgd9/uQ jCKfcSfNqGA11jNmTBlZPhvFgOixrgabKAB03VC1nLtGKhMZZLUCd0Rc0HBPTiLWGi3Q pRN2sgUpqlWunsWGctfPaM0S5QVe3Jq8/lErWIhs3xS39hZvSMKd20U4nlP4qKlAC4bR gWIu6F9BcwlsZs67+dT6acF3M1l6CsX1qu8oXufLVXOXpqvITNomKNdzc8JLCX+/NCaH koDQ== X-Gm-Message-State: AOAM533hfoBUUAE+mLN6yGIgKZxxBcetNPkHAIgE06izpqrgaDOIe6YB csgF+nM+KmUZ30PMZU4mwiM= X-Google-Smtp-Source: ABdhPJx6C95jvO3QDq44pW1gZW83dXpaVREAb1XxHJeUQjAZzFpUbbBxUSquWHfVsD7TZZbxEex6cQ== X-Received: by 2002:a05:6000:2c7:: with SMTP id o7mr55205536wry.0.1626095488839; Mon, 12 Jul 2021 06:11:28 -0700 (PDT) Received: from localhost ([137.220.125.106]) by smtp.gmail.com with ESMTPSA id u18sm12362244wmj.15.2021.07.12.06.11.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 12 Jul 2021 06:11:27 -0700 (PDT) From: luca.boccassi@gmail.com To: Ajit Khaparde Cc: dpdk stable Date: Mon, 12 Jul 2021 14:04:22 +0100 Message-Id: <20210712130551.2462159-27-luca.boccassi@gmail.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210712130551.2462159-1-luca.boccassi@gmail.com> References: <20210712130551.2462159-1-luca.boccassi@gmail.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 20.11.3 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 20.11.3 Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable yet. It will be pushed if I get no objections before 07/14/21. 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/bluca/dpdk-stable This queued commit can be viewed at: https://github.com/bluca/dpdk-stable/commit/ac656bd081befc325bd9cbe2bc5565e15e9829b4 Thanks. Luca Boccassi --- >From ac656bd081befc325bd9cbe2bc5565e15e9829b4 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 7baeaae431..a61e8320ae 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. -- 2.30.2 --- Diff of the applied patch vs upstream commit (please double-check if non-empty: --- --- - 2021-07-12 13:41:38.187967066 +0100 +++ 0027-doc-fix-default-burst-size-in-testpmd.patch 2021-07-12 13:41:36.286118361 +0100 @@ -1 +1 @@ -From 478614ee1f62e172c4d4770f157fc9bbb6563523 Mon Sep 17 00:00:00 2001 +From ac656bd081befc325bd9cbe2bc5565e15e9829b4 Mon Sep 17 00:00:00 2001 @@ -5,0 +6,2 @@ +[ upstream commit 478614ee1f62e172c4d4770f157fc9bbb6563523 ] + @@ -10 +11,0 @@ -Cc: stable@dpdk.org