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Date: Thu, 03 Jul 2008 09:21:10 +0200
From: Kevin Wolf <kwolf@suse.de>
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Subject: Re: [Qemu-devel] [patch 2/5] qemu-nbd: merge NBD client/server
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To: qemu-devel@nongnu.org
Cc: Laurent.Vivier@bull.net

Thiemo Seufer schrieb:
> Laurent.Vivier@bull.net wrote:
>> This patch allows to connect directly a disk image file to an NBD
>> device. It introduces the use of a unix socket (instead of inet).
>>
>> - To connect a file to a device:
>>
>> # qemu-nbd --connect=/dev/nbd0 my_disk.qcow2
>>
>> Then you can see directly your disk (no need of nbd-client):
>>
>> # fdisk -l /dev/nbd0
>>
>> Disk /dev/nbd0: 4294 MB, 4294967296 bytes
>> 255 heads, 63 sectors/track, 522 cylinders
>> Units = cylinders of 16065 * 512 = 8225280 bytes
>>
>>      Device Boot      Start         End      Blocks   Id  System
>> /dev/nbd0p1   *           1         492     3951958+  83  Linux
>> /dev/nbd0p2             493         522      240975    5  Extended
>> /dev/nbd0p5             493         522      240943+  82  Linux swap /
>> Solaris
>>
>> - To disconnect the file from the device:
>>
>> # qemu-nbd --disconnect /dev/nbd0
>>
>> Changelog:
>> - v2: call show_parts() from client and avoid the sleep(1). Thank you to
>> Avi and Anthony. Include my cleanup patch and comments from Carlo
>> Marcelo Arenas Belon.
>> - v3: allow to specify unix socket name with "--socket" and update 
>> documentation.
> 
> There's still a call to sleep() in this patch.

And that's fine, IMHO. sleep() is not bad per se. The remaining call is
not a "guess it'll take at most a second" style sleep but waiting in a
loop until the child is ready. You don't want the loop to eat up 100%
CPU, do you?

Kevin