From: Jerin Jacob <jerin.jacob@caviumnetworks.com>
To: Gavin Hu <gavin.hu@arm.com>
Cc: dev@dpdk.org, Honnappa.Nagarahalli@arm.com, steve.capper@arm.com,
Ola.Liljedahl@arm.com, nd@arm.com, stable@dpdk.org
Subject: Re: [dpdk-dev] [PATCH v3 2/3] ring: synchronize the load and store of the tail
Date: Sat, 29 Sep 2018 16:27:12 +0530 [thread overview]
Message-ID: <20180929105651.GB30457@jerin> (raw)
In-Reply-To: <1537172244-64874-2-git-send-email-gavin.hu@arm.com>
-----Original Message-----
> Date: Mon, 17 Sep 2018 16:17:23 +0800
> From: Gavin Hu <gavin.hu@arm.com>
> To: dev@dpdk.org
> CC: gavin.hu@arm.com, Honnappa.Nagarahalli@arm.com, steve.capper@arm.com,
> Ola.Liljedahl@arm.com, jerin.jacob@caviumnetworks.com, nd@arm.com,
> stable@dpdk.org
> Subject: [PATCH v3 2/3] ring: synchronize the load and store of the tail
> X-Mailer: git-send-email 2.7.4
>
>
> Synchronize the load-acquire of the tail and the store-release
> within update_tail, the store release ensures all the ring operations,
> enqueue or dequeue, are seen by the observers on the other side as soon
> as they see the updated tail. The load-acquire is needed here as the
> data dependency is not a reliable way for ordering as the compiler might
> break it by saving to temporary values to boost performance.
> When computing the free_entries and avail_entries, use atomic semantics
> to load the heads and tails instead.
>
> The patch was benchmarked with test/ring_perf_autotest and it decreases
> the enqueue/dequeue latency by 5% ~ 27.6% with two lcores, the real gains
> are dependent on the number of lcores, depth of the ring, SPSC or MPMC.
> For 1 lcore, it also improves a little, about 3 ~ 4%.
> It is a big improvement, in case of MPMC, with two lcores and ring size
> of 32, it saves latency up to (3.26-2.36)/3.26 = 27.6%.
>
> This patch is a bug fix, while the improvement is a bonus. In our analysis
> the improvement comes from the cacheline pre-filling after hoisting load-
> acquire from _atomic_compare_exchange_n up above.
>
> The test command:
> $sudo ./test/test/test -l 16-19,44-47,72-75,100-103 -n 4 --socket-mem=\
> 1024 -- -i
>
> Test result with this patch(two cores):
> SP/SC bulk enq/dequeue (size: 8): 5.86
> MP/MC bulk enq/dequeue (size: 8): 10.15
> SP/SC bulk enq/dequeue (size: 32): 1.94
> MP/MC bulk enq/dequeue (size: 32): 2.36
>
> In comparison of the test result without this patch:
> SP/SC bulk enq/dequeue (size: 8): 6.67
> MP/MC bulk enq/dequeue (size: 8): 13.12
> SP/SC bulk enq/dequeue (size: 32): 2.04
> MP/MC bulk enq/dequeue (size: 32): 3.26
>
> Fixes: 39368ebfc6 ("ring: introduce C11 memory model barrier option")
> Cc: stable@dpdk.org
>
> Signed-off-by: Gavin Hu <gavin.hu@arm.com>
> Reviewed-by: Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>
> Reviewed-by: Steve Capper <steve.capper@arm.com>
> Reviewed-by: Ola Liljedahl <Ola.Liljedahl@arm.com>
Tested with ThunderX2 server platform. Though it has minor performance impact on
non burst variants. For Burst variant, I could see similar performance
improvement and it is C11 semantically correct too.
Acked-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
Tested-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
next prev parent reply other threads:[~2018-09-29 10:57 UTC|newest]
Thread overview: 131+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-06 1:18 [dpdk-dev] [PATCH] ring: fix c11 memory ordering issue Gavin Hu
2018-08-06 9:19 ` Thomas Monjalon
2018-08-08 1:39 ` Gavin Hu
2018-08-07 3:19 ` [dpdk-dev] [PATCH v2] " Gavin Hu
2018-08-07 5:56 ` He, Jia
2018-08-07 7:56 ` Gavin Hu
2018-08-08 3:07 ` Jerin Jacob
2018-08-08 7:23 ` [dpdk-dev] [dpdk-stable] " Thomas Monjalon
2018-09-17 7:47 ` [dpdk-dev] [PATCH v3 1/3] app/testpmd: show errno along with flow API errors Gavin Hu
2018-09-17 7:47 ` [dpdk-dev] [PATCH v3 2/3] net/i40e: remove invalid comment Gavin Hu
2018-09-17 8:25 ` Gavin Hu (Arm Technology China)
2018-09-17 7:47 ` [dpdk-dev] [PATCH v3 3/3] doc: add cross compile part for sample applications Gavin Hu
2018-09-17 9:48 ` Jerin Jacob
2018-09-17 10:28 ` Gavin Hu (Arm Technology China)
2018-09-17 10:34 ` Jerin Jacob
2018-09-17 10:55 ` Gavin Hu (Arm Technology China)
2018-09-17 10:49 ` [dpdk-dev] [PATCH v4] " Gavin Hu
2018-09-17 10:53 ` [dpdk-dev] [PATCH v5] " Gavin Hu
2018-09-18 11:00 ` Jerin Jacob
2018-09-19 0:33 ` [dpdk-dev] [PATCH v6] " Gavin Hu
2018-09-17 8:11 ` [dpdk-dev] [PATCH v4 1/4] bus/fslmc: fix undefined reference of memsegs Gavin Hu
2018-09-17 8:11 ` [dpdk-dev] [PATCH v4 2/4] ring: read tail using atomic load Gavin Hu
2018-09-20 6:41 ` Jerin Jacob
2018-09-25 9:26 ` Gavin Hu (Arm Technology China)
2018-09-17 8:11 ` [dpdk-dev] [PATCH v4 3/4] ring: synchronize the load and store of the tail Gavin Hu
2018-09-17 8:11 ` [dpdk-dev] [PATCH v4 4/4] ring: move the atomic load of head above the loop Gavin Hu
2018-10-27 14:21 ` [dpdk-dev] [dpdk-stable] " Thomas Monjalon
2018-09-17 8:17 ` [dpdk-dev] [PATCH v3 1/3] ring: read tail using atomic load Gavin Hu
2018-09-17 8:17 ` [dpdk-dev] [PATCH v3 2/3] ring: synchronize the load and store of the tail Gavin Hu
2018-09-26 9:29 ` Gavin Hu (Arm Technology China)
2018-09-26 9:59 ` Justin He
2018-09-29 10:57 ` Jerin Jacob [this message]
2018-10-17 6:29 ` [dpdk-dev] [PATCH 1/2] " Gavin Hu
2018-10-17 6:29 ` [dpdk-dev] [PATCH 2/2] ring: move the atomic load of head above the loop Gavin Hu
2018-10-17 6:35 ` [dpdk-dev] [PATCH 1/2] ring: synchronize the load and store of the tail Gavin Hu (Arm Technology China)
2018-10-27 14:39 ` Thomas Monjalon
2018-10-27 15:00 ` Jerin Jacob
2018-10-27 15:13 ` Thomas Monjalon
2018-10-27 15:34 ` Jerin Jacob
2018-10-27 15:48 ` Thomas Monjalon
2018-10-29 2:51 ` Gavin Hu (Arm Technology China)
2018-10-29 2:57 ` Gavin Hu (Arm Technology China)
2018-10-29 10:16 ` Jerin Jacob
2018-10-29 10:47 ` Thomas Monjalon
2018-10-29 11:10 ` Jerin Jacob
2018-11-03 20:12 ` Mattias Rönnblom
2018-11-05 21:51 ` Honnappa Nagarahalli
2018-11-06 11:03 ` Mattias Rönnblom
2018-10-31 3:35 ` [dpdk-dev] [PATCH v2 0/2] rte ring c11 bug fix and optimization Gavin Hu
2018-10-31 10:26 ` [dpdk-dev] [PATCH v3 0/2] ring library with c11 memory model " Gavin Hu
2018-10-31 16:58 ` Thomas Monjalon
2018-11-01 9:53 ` [dpdk-dev] [PATCH v4 1/2] ring: synchronize the load and store of the tail Gavin Hu
2018-11-01 9:53 ` [dpdk-dev] [PATCH v4 2/2] ring: move the atomic load of head above the loop Gavin Hu
2018-11-01 17:26 ` Stephen Hemminger
2018-11-02 0:53 ` Gavin Hu (Arm Technology China)
2018-11-02 4:30 ` Honnappa Nagarahalli
2018-11-02 7:15 ` Gavin Hu (Arm Technology China)
2018-11-02 9:36 ` Thomas Monjalon
2018-11-02 11:23 ` Gavin Hu (Arm Technology China)
2018-10-31 10:26 ` [dpdk-dev] [PATCH v3 1/2] ring: synchronize the load and store of the tail Gavin Hu
2018-10-31 22:07 ` Stephen Hemminger
2018-11-01 9:56 ` Gavin Hu (Arm Technology China)
2018-10-31 10:26 ` [dpdk-dev] [PATCH v3 2/2] ring: move the atomic load of head above the loop Gavin Hu
2018-10-31 3:35 ` [dpdk-dev] [PATCH v2 1/2] ring: synchronize the load and store of the tail Gavin Hu
2018-10-31 3:35 ` [dpdk-dev] [PATCH v2 2/2] ring: move the atomic load of head above the loop Gavin Hu
2018-10-31 9:36 ` Thomas Monjalon
2018-10-31 10:27 ` Gavin Hu (Arm Technology China)
2018-11-01 9:53 ` [dpdk-dev] [PATCH v4 0/2] ring library with c11 memory model bug fix and optimization Gavin Hu
2018-11-02 11:21 ` [dpdk-dev] [PATCH v5 " Gavin Hu
2018-11-02 11:21 ` [dpdk-dev] [PATCH v5 1/2] ring: synchronize the load and store of the tail Gavin Hu
2018-11-05 9:30 ` Olivier Matz
2018-11-02 11:21 ` [dpdk-dev] [PATCH v5 2/2] ring: move the atomic load of head above the loop Gavin Hu
2018-11-02 11:43 ` Bruce Richardson
2018-11-03 1:19 ` Gavin Hu (Arm Technology China)
2018-11-03 9:34 ` Honnappa Nagarahalli
2018-11-05 13:17 ` [dpdk-dev] [dpdk-stable] " Thomas Monjalon
2018-11-05 13:41 ` Jerin Jacob
2018-11-05 9:44 ` [dpdk-dev] " Olivier Matz
2018-11-05 13:36 ` [dpdk-dev] [dpdk-stable] " Thomas Monjalon
2018-09-17 8:17 ` [dpdk-dev] [PATCH v3 3/3] " Gavin Hu
2018-09-26 9:29 ` Gavin Hu (Arm Technology China)
2018-09-26 10:06 ` Justin He
2018-09-29 7:19 ` Stephen Hemminger
2018-09-29 10:59 ` Jerin Jacob
2018-09-26 9:29 ` [dpdk-dev] [PATCH v3 1/3] ring: read tail using atomic load Gavin Hu (Arm Technology China)
2018-09-26 10:09 ` Justin He
2018-09-29 10:48 ` Jerin Jacob
2018-10-05 0:47 ` Gavin Hu (Arm Technology China)
2018-10-05 8:21 ` Ananyev, Konstantin
2018-10-05 11:15 ` Ola Liljedahl
2018-10-05 11:36 ` Ola Liljedahl
2018-10-05 13:44 ` Ananyev, Konstantin
2018-10-05 14:21 ` Ola Liljedahl
2018-10-05 15:11 ` Honnappa Nagarahalli
2018-10-05 17:07 ` Jerin Jacob
2018-10-05 18:05 ` Ola Liljedahl
2018-10-05 20:06 ` Honnappa Nagarahalli
2018-10-05 20:17 ` Ola Liljedahl
2018-10-05 20:29 ` Honnappa Nagarahalli
2018-10-05 20:34 ` Ola Liljedahl
2018-10-06 7:41 ` Jerin Jacob
2018-10-06 19:44 ` Ola Liljedahl
2018-10-06 19:59 ` Ola Liljedahl
2018-10-07 4:02 ` Jerin Jacob
2018-10-07 20:11 ` Ola Liljedahl
2018-10-07 20:44 ` Ola Liljedahl
2018-10-08 6:06 ` Jerin Jacob
2018-10-08 9:22 ` Ola Liljedahl
2018-10-08 10:00 ` Jerin Jacob
2018-10-08 10:25 ` Ola Liljedahl
2018-10-08 10:33 ` Gavin Hu (Arm Technology China)
2018-10-08 10:39 ` Ola Liljedahl
2018-10-08 10:41 ` Gavin Hu (Arm Technology China)
2018-10-08 10:49 ` Jerin Jacob
2018-10-10 6:28 ` Gavin Hu (Arm Technology China)
2018-10-10 19:26 ` Honnappa Nagarahalli
2018-10-08 10:46 ` Jerin Jacob
2018-10-08 11:21 ` Ola Liljedahl
2018-10-08 11:50 ` Jerin Jacob
2018-10-08 11:59 ` Ola Liljedahl
2018-10-08 12:05 ` Jerin Jacob
2018-10-08 12:20 ` Jerin Jacob
2018-10-08 12:30 ` Ola Liljedahl
2018-10-09 8:53 ` Olivier Matz
2018-10-09 3:16 ` Honnappa Nagarahalli
2018-10-08 14:43 ` Bruce Richardson
2018-10-08 14:46 ` Ola Liljedahl
2018-10-08 15:45 ` Ola Liljedahl
2018-10-08 5:27 ` Honnappa Nagarahalli
2018-10-08 10:01 ` Ola Liljedahl
2018-10-27 14:17 ` [dpdk-dev] [dpdk-stable] " Thomas Monjalon
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