linux-kernel - Re: [PATCH v2] irqchip: gicv3-its: Use NUMA aware memory allocation for ITS tables

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Date:   Thu, 13 Jul 2017 18:25:29 +0200
From:   Robert Richter <robert.richter@...ium.com>
To:     Shanker Donthineni <shankerd@...eaurora.org>
Cc:     Marc Zyngier <marc.zyngier@....com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>,
        Vikram Sethi <vikrams@...eaurora.org>,
        Ganapatrao Kulkarni <ganapatrao.kulkarni@...ium.com>,
        Eric Auger <eric.auger@...hat.com>
Subject: Re: [PATCH v2] irqchip: gicv3-its: Use NUMA aware memory allocation
 for ITS tables

On 10.07.17 10:53:45, Shanker Donthineni wrote:
> 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.
> 
> Signed-off-by: Shanker Donthineni <shankerd@...eaurora.org>
> Tested-by: Ganapatrao Kulkarni <ganapatrao.kulkarni@...ium.com>
> ---
>  drivers/irqchip/irq-gic-v3-its.c | 36 ++++++++++++++++++++----------------
>  1 file changed, 20 insertions(+), 16 deletions(-)

> @@ -1773,7 +1777,7 @@ static int __init its_probe_one(struct resource *res,
>  out_free_tables:
>  	its_free_tables(its);
>  out_free_cmd:
> -	free_pages((unsigned long)its->cmd_base, get_order(ITS_CMD_QUEUE_SZ));
> +	__free_pages(virt_to_page(its->cmd_base), get_order(ITS_CMD_QUEUE_SZ));

This change is not required as free_pages() can be used here directly.

-Robert

>  out_free_its:
>  	kfree(its);
>  out_unmap: