From: Thomas Monjalon <thomas.monjalon@6wind.com>
To: Yuanhan Liu <yuanhan.liu@linux.intel.com>,
Jianbo Liu <jianbo.liu@linaro.org>,
Jerin Jacob <jerin.jacob@cavium.com>,
Jan Viktorin <viktorin@rehivetech.com>,
Chao Zhu <chaozhu@linux.vnet.ibm.com>
Cc: dev@dpdk.org, Tan Jianfeng <jianfeng.tan@intel.com>,
Wang Zhihong <zhihong.wang@intel.com>,
Olivier Matz <olivier.matz@6wind.com>,
Maxime Coquelin <maxime.coquelin@redhat.com>,
"Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: [dpdk-dev] [dpdk-stable] [PATCH 1/2] net/virtio: fix performance regression due to TSO enabling
Date: Wed, 11 Jan 2017 15:51:22 +0100 [thread overview]
Message-ID: <1610499.AMUobBPor6@xps13> (raw)
In-Reply-To: <1484108832-19907-2-git-send-email-yuanhan.liu@linux.intel.com>
2017-01-11 12:27, Yuanhan Liu:
> The fact that virtio net header is initiated to zero in PMD driver
> init stage means that these costly writes are unnecessary and could
> be avoided:
>
> if (hdr->csum_start != 0)
> hdr->csum_start = 0;
>
> And that's what the macro ASSIGN_UNLESS_EQUAL does. With this, the
> performance drop introduced by TSO enabling is recovered: it could
> be up to 20% in micro benchmarking.
This patch is adding a condition to assignments.
We need a benchmark on other architectures like ARM. Please anyone?
[...]
> +/* avoid write operation when necessary, to lessen cache issues */
> +#define ASSIGN_UNLESS_EQUAL(var, val) do { \
> + if ((var) != (val)) \
> + (var) = (val); \
> +} while (0)
next prev parent reply other threads:[~2017-01-11 14:51 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-11 4:27 [dpdk-dev] [PATCH 0/2] net/virtio: optimize virtio net header reset Yuanhan Liu
2017-01-11 4:27 ` [dpdk-dev] [PATCH 1/2] net/virtio: fix performance regression due to TSO enabling Yuanhan Liu
2017-01-11 7:59 ` Maxime Coquelin
2017-01-11 8:08 ` Yuanhan Liu
2017-01-11 8:22 ` Olivier MATZ
2017-01-11 14:51 ` Thomas Monjalon [this message]
2017-01-12 2:30 ` [dpdk-dev] [dpdk-stable] " Yuanhan Liu
2017-01-12 15:02 ` Jan Viktorin
2017-01-13 6:13 ` Yuanhan Liu
2017-01-16 7:12 ` Yuanhan Liu
[not found] ` <46569522-b2c3-2a33-9111-049b73c79760@stud.fit.vutbr.cz>
[not found] ` <20170116111256.GA11439@yliu-dev.sh.intel.com>
[not found] ` <8e8178c6-caa2-1b6e-10a0-c83820868db5@stud.fit.vutbr.cz>
2017-01-16 11:21 ` Yuanhan Liu
[not found] ` <a12848b4-76ef-29bc-f512-81bd8c1b9b76@stud.fit.vutbr.cz>
2017-01-30 13:30 ` Yuanhan Liu
2017-01-30 13:54 ` Maxime Coquelin
2017-01-30 14:10 ` Yuanhan Liu
2017-01-11 4:27 ` [dpdk-dev] [PATCH 2/2] net/virtio: optimize header reset on any layout Yuanhan Liu
2017-01-11 8:01 ` Maxime Coquelin
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