[Samba 4.2] Why AIO at times, does not seem to work until I restart Samba?

Jeremy Allison jra at samba.org
Tue Mar 17 15:23:15 MDT 2015

On Tue, Mar 17, 2015 at 05:42:26PM +0530, Raj Kumar Sanpui wrote:
> Hello Samba developers,
> I am using Samba 4.2 version and using the AIO support (read and write)
> using the options mentioned in smb.conf.
> I am copying files from a Linux machine via Samba to Windows. The files in
> Linux are hosted on a fuse filesystem, hence copying is expected to be
> relaatively slow, but using AIO i gained some performance gain.
> The issue is:
> I copy 1 file to Windows, no issues. works great, and i can browse my Linux
> filesystem at speed in WIndows as the copy is going on.
> I copy 2 files from Linux to Windows, and here I can no longer parallely
> browse the Linux filesystem, and it keeps me waiting till the file starts
> copying.
> And here onwards, AIo no longer works, even if i try copying single file,
> until I reload/restart Samba.
> I enabled the debug mode to 10, and noticed AIO read is indeed scheduled:

Network traces would help here, as would debug level 10's. 4.2
should be built naturally with pthread support and so should
be using a threadpool to schedule multiple IO's here.

First things first - can you try exactly the same test
against a ext4 filesystem - not your FUSE thing - and
see if the async IO calls are working correctly there ?

This will help work out if it's a strange FUSE interaction
or something else about how you might have built the code.



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