From: Randy Dunlap <rdunlap@infradead.org>
To: loody <miloody@gmail.com>
Cc: NeilBrown <neilb@suse.de>, Linux-FSDevel <linux-fsdevel@vger.kernel.org>
Subject: Re: dummy file read periodically for external USB Hard Disk
Date: Fri, 18 Jul 2014 11:13:25 -0700 [thread overview]
Message-ID: <53C963C5.5090209@infradead.org> (raw)
In-Reply-To: <CANudz+vOiXTQnsfe=d==zQYFOtnQ=ye1HLdF2FdWJPEchfBNNA@mail.gmail.com>
On 07/18/2014 10:31 AM, loody wrote:
> hi Randy and All:
>
>>
>> It means that the <buffer> still is not aligned to a 512-byte boundary.
>> Try
>> char buffer[1024] __attribute__ ((aligned(1024)));
>>
>> Well, that is aligned to 1024 bytes, not 512, but whatever.
> the suggestion you gave to me works ^^
> is there any alignment check in kernel FS such that it will directly
> output to device instead of getting data from page cache?
Not sure that I understand your question, but I think that using
O_DIRECT in the open() call attempts to do what you are asking.
Please read 'man open' and search for O_DIRECT.
--
~Randy
next prev parent reply other threads:[~2014-07-18 18:13 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-07 14:42 dummy file read periodically for external USB Hard Disk loody
2014-07-08 3:01 ` NeilBrown
2014-07-08 3:17 ` Dave Jones
2014-07-08 15:00 ` loody
2014-07-09 14:13 ` loody
2014-07-10 0:47 ` NeilBrown
2014-07-11 9:04 ` loody
2014-07-12 3:01 ` Randy Dunlap
2014-07-18 17:31 ` loody
2014-07-18 18:13 ` Randy Dunlap [this message]
2014-07-19 10:59 ` loody
2014-07-19 11:02 ` loody
2014-07-19 21:19 ` Randy Dunlap
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