Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Mon, 18 Mar 2019 14:07:57 +0100
From:   Michal Hocko <mhocko@kernel.org>
To:     Pankaj Suryawanshi <pankaj.suryawanshi@einfochips.com>
Cc:     "linux-mm@kvack.org" <linux-mm@kvack.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "minchan@kernel.org" <minchan@kernel.org>,
        Kirill Tkhai <ktkhai@virtuozzo.com>
Subject: Re: mm/cma.c: High latency for cma allocation
Message-ID: <20190318130757.GG8924@dhcp22.suse.cz>
References: <SG2PR02MB3098E44824F5AA69BC04F935E8470@SG2PR02MB3098.apcprd02.prod.outlook.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <SG2PR02MB3098E44824F5AA69BC04F935E8470@SG2PR02MB3098.apcprd02.prod.outlook.com>
User-Agent: Mutt/1.10.1 (2018-07-13)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Mon 18-03-19 12:58:28, Pankaj Suryawanshi wrote:
> Hello,
> 
> I am facing issue of high latency in CMA allocation of large size buffer.
> 
> I am frequently allocating/deallocation CMA memory, latency of allocation is very high.
> 
> Below are the stat for allocation/deallocation latency issue.
> 
> (390100 kB),  latency 29997 us
> (390100 kB),  latency 22957 us
> (390100 kB),  latency 25735 us
> (390100 kB),  latency 12736 us
> (390100 kB),  latency 26009 us
> (390100 kB),  latency 18058 us
> (390100 kB),  latency 27997 us
> (16 kB), latency 560 us
> (256 kB), latency 280 us
> (4 kB), latency 311 us
> 
> I am using kernel 4.14.65 with android pie(9.0).
> 
> Is there any workaround or solution for this(cma_alloc latency) issue ?

Do you have any more detailed information on where the time is spent?
E.g. migration tracepoints?

-- 
Michal Hocko
SUSE Labs