From: "Frantisek Rysanek" <Frantisek.Rysanek@post.cz>
To: "Jörn Engel" <joern@logfs.org>, linux-kernel@vger.kernel.org
Subject: Re: [noob q. on block layer] block IO read-ahead during sequential *write*?
Date: Mon, 07 Jan 2008 16:51:22 +0100 [thread overview]
Message-ID: <4782588A.3856.1B9C57D9@localhost> (raw)
In-Reply-To: <20080107124952.GA8201@lazybastard.org>
On 7 Jan 2008 at 13:49, Jörn Engel wrote:
>
> If you retry the dd with bs=4096 (or whatever your architecture's page
> size happens to be), does this still occur?
>
> JĂśrn
>
wow, thanks, it works, this is so obvious.
I tend to use values like bs=512000 or suchlike, but probably never
stroke this particular value when I was looking at iostat.
Must've missed that modulo 4096 somehow.
Seems like cp is using 512B per transaction, judging by how slow the
transfer goes. If I use bs=500000 or even bs=1024, it goes faster.
Have a nice day :-}
Frank Rysanek
prev parent reply other threads:[~2008-01-07 15:45 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-01-07 12:25 [noob q. on block layer] block IO read-ahead during sequential *write*? Frantisek Rysanek
2008-01-07 12:49 ` Jörn Engel
2008-01-07 15:51 ` Frantisek Rysanek [this message]
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