Re: [Nbd] [PATCH] Make integrity tests respect request ordering.

[Wouter Verhelst <w@...112...>]

On Mon, Jun 06, 2011 at 09:43:33PM +0100, Alex Bligh wrote:
> Prior to this patch, the integrity test fired reads and writes as
> quickly as they could at the server. This included firing overlapping
> reads and writes, before the prior read or write was acknowledged.
> Under the protocol, the server is permitted to reorder reads and
> writes until they are acknowledged. Whilst nbd-server does not
> currently reorder reads or writes, this caused a "false failure"
> in other servers that do reorder reads and writes. Also, the workload
> as sent was unrealistic (in that servers do not normally have
> overlapping reads and writes in their queue).
> 
> This patch maintains a record of the reads and writes inflight, and
> ensures that:
> 
> 1. If any block X is covered by an inflight write request, then
>    no other request covering block X will be sent until a reply
>    to such inflight write is received.
> 
> 2. If any block X is covered by an inflight read or write request,
>    then no write request covering block X will be sent until a reply
>    to such inflight request is received.
> 
> In otherwords, disallow all overlapping inflight requests, except
> overlapping inflight reads, which are permitted.
> 
> The "-l" option to nbd-tester-client can be used to turn on
> looseordering, IE not do the above.
> 
> I have tested this on nbd-server (no change as expected) and on
> a server which does reorder requests (which now passes the tests).

Merged, thanks.

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