Re: [Nbd] [PATCH] Only send one reply on oversize writes

[Alex Bligh <alex@...872...>]

Wouter,

--On 28 May 2011 13:53:30 +0100 Alex Bligh <alex@...872...> wrote:

> > There's nothing to say that the seek offset won't be duplicated, either.
> > Probably best to create our own handles, indeed.
>
> I meant the seek offset into the transaction log (which is monotonic)
> but given we'll have a hash there anyway, yes, probably just creating
> random ones is best.

I did this, and produced a test for oversize reads & writes. This was
clearly worth doing as I found 3 bugs in our handling of oversize
transactions. Given these all have disk corruption potential, I hope
you can get them into your weekend release.

I reintroduced the duplicate reply bug, and integrityhuge caught
it immediately.

Out of interest, I also fixed the speed calculation in integritytest()
(stupid error on my part). This now shows the integrity test with normal
data (even full of flushes and FUAs) runs far faster than the throughput
test, and the huge integrity test runs even faster! I'm getting
(to an SSD on a Macbook Air via VMWare) about 10MB/s for throughput
test, and 67MB/s for integrity and 130 for integrityhuge. I can only
explain this by the fact that using even slightly large read/write
sizes than 1K seems to be far more efficient.

I'm now reasonably confident that between the 2 integrity test instances,
we are comprehensively testing the server.

You will be pleased to hear I don't plan to do anything more for
this weekend's release, unless you find some bugs in my code of
course.

--
Alex Bligh