From: Jianbo Liu <jianbo.liu@linaro.org>
To: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>,
"Zhang, Helin" <helin.zhang@intel.com>,
"jerin.jacob@caviumnetworks.com"
<jerin.jacob@caviumnetworks.com>
Subject: Re: [dpdk-dev] [PATCH 1/2] net/ixgbe: calculate the correct number of received packets in bulk alloc function
Date: Fri, 3 Feb 2017 14:22:15 +0800 [thread overview]
Message-ID: <CAP4Qi391K_DOZsxVbG7kp5BFUr0iJDFyxbVYNqmPzYPptK4qnw@mail.gmail.com> (raw)
In-Reply-To: <2601191342CEEE43887BDE71AB9772583F10FF87@irsmsx105.ger.corp.intel.com>
On 2 February 2017 at 00:19, Ananyev, Konstantin
<konstantin.ananyev@intel.com> wrote:
> Hi,
>
>> -----Original Message-----
>> From: Jianbo Liu [mailto:jianbo.liu@linaro.org]
>> Sent: Monday, December 19, 2016 6:09 AM
>> To: dev@dpdk.org; Zhang, Helin <helin.zhang@intel.com>; Ananyev, Konstantin <konstantin.ananyev@intel.com>;
>> jerin.jacob@caviumnetworks.com
>> Cc: Jianbo Liu <jianbo.liu@linaro.org>
>> Subject: [PATCH 1/2] net/ixgbe: calculate the correct number of received packets in bulk alloc function
>>
>> To get better performance, Rx bulk alloc recv function will scan 8 descriptors
>> in one time, but the statuses are not consistent on ARM platform because
>> the memory allocated for Rx descriptors is cacheable hugepages.
>> This patch is to calculate the number of received packets by scanning DD bit
>> sequentially, and stops when meeting the first packet with DD bit unset.
>>
>> Signed-off-by: Jianbo Liu <jianbo.liu@linaro.org>
>> ---
>> drivers/net/ixgbe/ixgbe_rxtx.c | 12 ++++++++----
>> 1 file changed, 8 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/net/ixgbe/ixgbe_rxtx.c b/drivers/net/ixgbe/ixgbe_rxtx.c
>> index b2d9f45..2866bdb 100644
>> --- a/drivers/net/ixgbe/ixgbe_rxtx.c
>> +++ b/drivers/net/ixgbe/ixgbe_rxtx.c
>> @@ -1402,17 +1402,21 @@ ixgbe_rx_scan_hw_ring(struct ixgbe_rx_queue *rxq)
>> for (i = 0; i < RTE_PMD_IXGBE_RX_MAX_BURST;
>> i += LOOK_AHEAD, rxdp += LOOK_AHEAD, rxep += LOOK_AHEAD) {
>> /* Read desc statuses backwards to avoid race condition */
>> - for (j = LOOK_AHEAD-1; j >= 0; --j)
>> + for (j = LOOK_AHEAD - 1; j >= 0; --j) {
>> s[j] = rte_le_to_cpu_32(rxdp[j].wb.upper.status_error);
>> -
>> - for (j = LOOK_AHEAD - 1; j >= 0; --j)
>> pkt_info[j] = rte_le_to_cpu_32(rxdp[j].wb.lower.
>> lo_dword.data);
>> + }
>> +
>> + rte_smp_rmb();
>
> If reads can be reordered, shouldn't we fill pkt_info[] after smp_rmb() here?
The barrier is to forbid the reordering from the following readings,
which will count the number of actual received packets.
And as wb.uper and wb.lower of one descriptor are in the same
cacheline, could it be better to read them at the same time?.
> As another nit - with rmb() in and because you are looking the first gap in s[] now,
> no need to read TXDs in backward order.
Reading backward is just to keep as it is for x86 platform.
> How it looks to me (as a suggestion):
>
> for (j = 0; j != LOOK_AHEAD; j++)
> s[j] = rte_le_to_cpu_32(rxdp[j].wb.upper.status_error);
>
> rte_smp_rmb();
>
> for (j = 0; j < LOOK_AHEAD && (s[j] & IXGBE_RXDADV_STAT_DD) != 0; j++)
> ;
>
> for (j = 0; j < nb_dd; ++j) {
> pkt_info[j] = rte_le_to_cpu_32(rxdp[j].wb.lower.lo_dword.data);
> ....
>
> Konstantin
>
>
>>
>> /* Compute how many status bits were set */
>> nb_dd = 0;
>> for (j = 0; j < LOOK_AHEAD; ++j)
>> - nb_dd += s[j] & IXGBE_RXDADV_STAT_DD;
>> + if (s[j] & IXGBE_RXDADV_STAT_DD)
>> + ++nb_dd;
>> + else
>> + break;
>>
>> nb_rx += nb_dd;
>>
>> --
>> 2.4.11
>
next prev parent reply other threads:[~2017-02-03 6:22 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-19 6:09 Jianbo Liu
2016-12-19 6:09 ` [dpdk-dev] [PATCH 2/2] net/ixgbe: calculate correct number of received packets for ARM NEON-version vPMD Jianbo Liu
2016-12-21 10:08 ` Jerin Jacob
2016-12-21 11:03 ` Bruce Richardson
2016-12-22 1:18 ` Jianbo Liu
2016-12-22 1:05 ` Jianbo Liu
2017-02-01 16:19 ` [dpdk-dev] [PATCH 1/2] net/ixgbe: calculate the correct number of received packets in bulk alloc function Ananyev, Konstantin
2017-02-03 6:22 ` Jianbo Liu [this message]
2017-02-03 11:38 ` Ananyev, Konstantin
2017-02-04 3:37 ` Jianbo Liu
2017-02-04 9:37 ` [dpdk-dev] [PATCH v2 " Jianbo Liu
2017-02-04 9:37 ` [dpdk-dev] [PATCH v2 2/2] net/ixgbe: calculate correct number of received packets for ARM NEON-version vPMD Jianbo Liu
2017-02-04 13:26 ` [dpdk-dev] [PATCH v2 1/2] net/ixgbe: calculate the correct number of received packets in bulk alloc function Ananyev, Konstantin
2017-02-08 18:02 ` Ferruh Yigit
2017-02-08 18:53 ` Ananyev, Konstantin
2017-02-08 19:53 ` Ananyev, Konstantin
2017-02-09 3:49 ` Jianbo Liu
2017-02-04 16:37 ` [dpdk-dev] [PATCH v3 " Jianbo Liu
2017-02-04 16:37 ` [dpdk-dev] [PATCH v3 2/2] net/ixgbe: calculate correct number of received packets for ARM NEON-version vPMD Jianbo Liu
2017-02-04 16:39 ` [dpdk-dev] [PATCH v3 1/2] net/ixgbe: calculate the correct number of received packets in bulk alloc function Jianbo Liu
2017-02-09 4:05 ` [dpdk-dev] [PATCH v4 " Jianbo Liu
2017-02-09 4:05 ` [dpdk-dev] [PATCH v4 2/2] net/ixgbe: calculate correct number of received packets for ARM NEON-version vPMD Jianbo Liu
2017-02-09 12:43 ` Ferruh Yigit
2017-02-09 12:39 ` [dpdk-dev] [PATCH v4 1/2] net/ixgbe: calculate the correct number of received packets in bulk alloc function Ferruh Yigit
2017-02-09 12:42 ` Ferruh Yigit
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAP4Qi391K_DOZsxVbG7kp5BFUr0iJDFyxbVYNqmPzYPptK4qnw@mail.gmail.com \
--to=jianbo.liu@linaro.org \
--cc=dev@dpdk.org \
--cc=helin.zhang@intel.com \
--cc=jerin.jacob@caviumnetworks.com \
--cc=konstantin.ananyev@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).