Date: Fri, 23 Apr 2010 09:42:53 +0300 From: Andriy Gapon <avg@icyb.net.ua> To: Pawel Jakub Dawidek <pjd@FreeBSD.org> Cc: freebsd-fs@FreeBSD.org, freebsd-geom@FreeBSD.org Subject: Re: vdev_geom_io: parallelize ? Message-ID: <4BD1416D.30207@icyb.net.ua> In-Reply-To: <20100423060850.GB1670@garage.freebsd.pl> References: <4BD0C802.3000004@icyb.net.ua> <20100423060850.GB1670@garage.freebsd.pl>
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on 23/04/2010 09:08 Pawel Jakub Dawidek said the following:
> On Fri, Apr 23, 2010 at 01:04:50AM +0300, Andriy Gapon wrote:
>> Just thinking out loud.
>>
>> Currently ZFS vdev_geom_io does something like:
>> for (...) {
>> ...
>> g_io_request(...);
>> biowait(...);
>> ...
>> }
>> I/O is done in MAXPHYS chunks.
>>
>> If that was changed to first issuing all the requests and only after that
>> waiting on them, could there be any performance benefit?
>> Or cases of vdev_geom_io with size > MAXPHYS are too rare?
>> Or something else?
>
> The vdev_geom_io() function is there only to read ZFS labels, it is not
> used during regular I/O. Regular I/O requests are handled asynchronously
> by the vdev_geom_io_start() function.
Oops. Thanks!
--
Andriy Gapon
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