Mailing-List: contact dev-help@harmony.apache.org; run by ezmlm
Precedence: bulk
Reply-To: dev@harmony.apache.org
Received-SPF: pass (athena.apache.org: domain of alexei.fedotov@gmail.com
 designates 66.249.92.169 as permitted sender)
DomainKey-Signature: a=rsa-sha1; c=nofws;
        d=gmail.com; s=beta;
        h=received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references;
        b=mkatyVH0XmB6N7ZH80yoYBTmqP51ofVO2PFrqL0NYoqE0Plochg4VvuHvwFvQbsqCdARYH1/cpAakI+8b3zuWhYV9EzJtuT8EDWEWNbl5yHtbdAvUAZra2DajFzvQKn3l5/C/s+joTabEHBsvL40YgJ3lJjIy24vDMDqbGolOTI=
Message-ID: <c30d70960710010944k71f299cbm35ed7a224201b3a8@mail.gmail.com>
Date: Mon, 1 Oct 2007 20:44:46 +0400
From: "Alexei Fedotov" <alexei.fedotov@gmail.com>
To: dev@harmony.apache.org
Subject: Re: [classlib][nio] epoll()-based Selector
In-Reply-To: <4bebff790710010849q3116964br7d85dc5a5b5f20a7@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
References: <4bebff790710010849q3116964br7d85dc5a5b5f20a7@mail.gmail.com>

Great job, Aleksey! x320 looks fantastic.

I recall that one of my former colleagues hacked callback-based
dispatch into Linux kernel to process IP-telephony calls quickly. It's
nice to know that now anyone can use this feature just by calling
epoll.

On 10/1/07, Aleksey Shipilev <aleksey.shipilev@gmail.com> wrote:
> Hi all,
>
> I would like to present the epoll()-based java.nio.channels.Selector
> for Harmony. Epoll facility [1] was developed as the part on Linux
> Kernel starting from version 2.5.44, and its interface was finalized
> starting before 2.6.x kernels. Epoll is generally driven by callbacks
> inside the kernel and thus it strives to be O(1), whereas legacy
> poll() and select() are driven by traversing linked lists and thus
> being O(n).
>
> You can find draft implementation at HARMONY-4879 [2]. This version is
> ready to play, but not intended for inclusion, since there are a
> couple of performance problems persist (like possible O(n^2) at
> processSelectResults()). I will try to eliminate them in several days.
> However, this patch successfully passes JUnit tests and might be ready
> to be tried on some networking-heavy workloads.
>
> Speaking about performance results, simple test which registers 2000
> channels on one Selector and then continuously calls selectNow()
> reveals this:
>
> Harmony-r576670:
>  connect time: 100538 msecs
>  selectNow() time (10000 times): 27777 msecs
>
> Harmony-r576670 + HARMONY-4879:
>  connect time: 832 msecs
>  selectNow() time (10000 times): 87 msecs
>
> Speedups:
>  connect: 120x
>  selectNow(): 320x
>
> More details are in JIRA.
>
> Is someone interested in the topic?
> I would like to collaborate with you then - to prevent duplication of work :)
>
> [1] http://lse.sourceforge.net/epoll/index.html
> [2] https://issues.apache.org/jira/browse/HARMONY-4879
>


-- 
With best regards,
Alexei,
ESSD, Intel