sftp prefetch disabled

[Robert Collins]

On Mon, 2006-07-17 at 12:30 -0500, John Arbash Meinel wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
> 
> Robert disabled sftp prefetch a while ago, and I'm trying to figure out why.
> 
> Specifically revision id:
> robertc at robertcollins.net-20060419233208-2ed6906796994316
> date: Thu 2006-04-20 09:32:08 +1000
> 
> Has the commit message:
> ... Disable all SFTP prefetching for known paramikos - direct readv
> support is now a TODO.
> 
> 
> There are 2 problems...
> 
> 1) The latest paramiko is now 1.6.1, so if we want prefetching disabled,
> we need to update the version test.
> 2) Why did we want to disable prefetch entirely? Just because readv
> would be messed up by it?
> 
> Robey: Can you comment about prefetch support. It used to be disabled
> for < 1.5.2 because there were bugs. I assume it has worked since then.
> 
> I will probably do a little bit of testing to see what effect prefetch
> has. (I thought I was, until I dug deep enough to see this). My gut
> feeling is that for readv() it would be a net loss, but for a plain
> 'get()' it would be good.
> 
> Anyway, I was just hoping to get clarification. From Robert: Do you want
> to disable it completely? From Robey: Are there any known bugs with
> prefetch that we should disable before a certain point?

As Robey says - it was buggy. Specifically when we started doing
emulated readv calls, prefetch on *all* paramikos at that time
intereracted very badly. (By badly, I mean crash).

Its on my todo to test bzr with 0.6.x paramiko and see if no warnings
are emitted (last time I tried, it spewed awfully). Related to that
LarstiQ has organised an update to the package to 0.6, and this is part
of that testing.

Rob


-- 
GPG key available at: <http://www.robertcollins.net/keys.txt>.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 191 bytes
Desc: This is a digitally signed message part
Url : https://lists.ubuntu.com/archives/bazaar/attachments/20060720/23cf477d/attachment.pgp