linux-kernel - Re: [PATCH v3] irqchip: gicv3-its: Use NUMA aware memory allocation for ITS tables

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Date:   Thu, 13 Dec 2018 11:54:43 +0000
From:   Marc Zyngier <marc.zyngier@....com>
To:     Shameer Kolothum <shameerali.kolothum.thodi@...wei.com>,
        linux-kernel@...r.kernel.org
Cc:     shankerd@...eaurora.org, ganapatrao.kulkarni@...ium.com,
        Robert.Richter@...ium.com, guohanjun@...wei.com,
        john.garry@...wei.com, linux-arm-kernel@...ts.infradead.org,
        linuxarm@...wei.com
Subject: Re: [PATCH v3] irqchip: gicv3-its: Use NUMA aware memory allocation
 for ITS tables

On 13/12/2018 10:59, Shameer Kolothum wrote:
> From: Shanker Donthineni <shankerd@...eaurora.org>
> 
> The NUMA node information is visible to ITS driver but not being used
> other than handling hardware errata. ITS/GICR hardware accesses to the
> local NUMA node is usually quicker than the remote NUMA node. How slow
> the remote NUMA accesses are depends on the implementation details.
> 
> This patch allocates memory for ITS management tables and command
> queue from the corresponding NUMA node using the appropriate NUMA
> aware functions. This change improves the performance of the ITS
> tables read latency on systems where it has more than one ITS block,
> and with the slower inter node accesses.
> 
> Apache Web server benchmarking using ab tool on a HiSilicon D06
> board with multiple numa mem nodes shows Time per request and
> Transfer rate improvements of ~3.6% with this patch.
> 
> Signed-off-by: Shanker Donthineni <shankerd@...eaurora.org>
> Signed-off-by: Hanjun Guo <guohanjun@...wei.com>
> Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@...wei.com>
> ---
> 
> This is to revive the patch originally sent by Shanker[1] and 
> to back it up with a benchmark test. Any further testing of
> this is most welcome.
> 
> v2-->v3
>  -Addressed comments to use page_address().
>  -Added Benchmark results to commit log.
>  -Removed T-by from Ganapatrao for now.
> 
> v1-->v2
>  -Edited commit text.
>  -Added Ganapatrao's tested-by.
> 
> Benchmark test details:
> --------------------------------
> Test Setup:
> -D06 with dimm on node 0(Sock#0) and 3 (Sock#1).
> -ITS belongs to numa node 0.
> -Filesystem mounted on a PCIe NVMe based disk.
> -Apache server installed on D06.
> -Running ab benchmark test in concurrency mode from a remote m/c
>  connected to D06 via  hns3(PCIe) n/w port.
>  "ab -k -c 750 -n 2000000 http://10.202.225.188/"
> 
> Test results are avg. of 15 runs.
> 
> For 4.20-rc1  Kernel,
> ----------------------------
> Time per request(mean, concurrent)  = 0.02753[ms]  
> Transfer Rate = 416501[Kbytes/sec]
> 
> For 4.20-rc1 +  this patch,
> ----------------------------------
> Time per request(mean, concurrent)  = 0.02653[ms]  
> Transfer Rate = 431954[Kbytes/sec]
> 
> % improvement ~3.6%
> 
> vmstat shows around 170K-200K interrupts per second.
> 
> ~# vmstat 1 -w
> procs -----------------------memory-- -  -system--
>  r  b         swpd         free            in             
>  5  0            0     30166724          102794 
>  9  0            0     30141828          171148 
>  5  0            0     30150160          207185 
> 13  0            0     30145924          175691 
> 15  0            0     30140792          145250 
> 13  0            0     30135556          201879 
> 13  0            0     30134864          192391 
> 10  0            0     30133632          168880 
> ....
> 
> [1] https://patchwork.kernel.org/patch/9833339/

The figures certainly look convincing. I'd need someone from Cavium to
benchmark it on their hardware and come back with results so that we can
make a decision on this.

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...