[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Qemu-devel] [PATCH 12/12] nbd: split requests

From: Paolo Bonzini
Subject: Re: [Qemu-devel] [PATCH 12/12] nbd: split requests
Date: Fri, 09 Sep 2011 17:33:57 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:6.0) Gecko/20110816 Thunderbird/6.0

On 09/09/2011 04:52 PM, Nicholas Thomas wrote:
>  +/* qemu-nbd has a limit of slightly less than 1M per request.  For safety,
>  + * transfer at most 512K per request. */
>  +#define NBD_MAX_SECTORS 1024

As far as I'm aware, the limit of 1MiB - header size is common to all
NBD servers. I'm not aware of anything at all that'll fail on a 768K
request but succeed in the exact same circumstances on a 512K request.
Again, this is a performance consideration - each request is relatively
slow, so you don't want them to be unnecessarily small.

Yes, it should probably be bumped to 1536 or 2040 (to keep requests 4k-aligned). I wasn't sure about the limit. I've never seen requests that big anyway.


reply via email to

[Prev in Thread] Current Thread [Next in Thread]