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From: Greg KH <greg@kroah.com>
To: Ren? Rebe <rene@exactcode.de>
Cc: linux-kernel@vger.kernel.org, Oliver Neukum <oliver@neukum.org>
Subject: Re: MAX_USBFS_BUFFER_SIZE
Date: Thu, 2 Mar 2006 08:47:20 -0800	[thread overview]
Message-ID: <20060302164720.GA31076@kroah.com> (raw)
In-Reply-To: <200603021703.26549.rene@exactcode.de>

On Thu, Mar 02, 2006 at 05:03:26PM +0100, Ren? Rebe wrote:
> Hi,
> 
> On Wednesday 01 March 2006 22:54, Greg KH wrote:
> 
> > > > Why not just send down 2 urbs with that size then, that would keep the
> > > > pipe quite full.
> > > 
> > > Because that requires even more modifications to libusb and sane (i_usb) ...
> > 
> > No, do it in your application I mean.
> 
> Ok, tweaking libusb to queue N URBs for reads to be split (resulting in 9 URBs
> in my usecase) I see a nearly 100% improvement here (2 times faster).
> 
> How many URBs may I queue? Nearly infinite (in my case that would be max 64)
> or is there some tiny static list somewhere in the affected code-path?

There is no static list that I know of, as it is all just pointers.
Just don't DOS the kernel by sending it an infinate ammount of memory :)

More details can be found on the linux-usb-devel list if you ask there.

thanks,

greg k-h

  reply	other threads:[~2006-03-02 16:47 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-03-01 20:16 MAX_USBFS_BUFFER_SIZE René Rebe
2006-03-01 20:53 ` MAX_USBFS_BUFFER_SIZE Oliver Neukum
2006-03-01 21:32 ` MAX_USBFS_BUFFER_SIZE Greg KH
2006-03-01 21:42   ` MAX_USBFS_BUFFER_SIZE René Rebe
2006-03-01 21:54     ` MAX_USBFS_BUFFER_SIZE Greg KH
2006-03-01 22:34       ` MAX_USBFS_BUFFER_SIZE Olivier Galibert
2006-03-01 22:41         ` MAX_USBFS_BUFFER_SIZE Greg KH
2006-03-01 23:25           ` MAX_USBFS_BUFFER_SIZE Olivier Galibert
2006-03-01 23:37             ` MAX_USBFS_BUFFER_SIZE Greg KH
2006-03-02  9:04       ` MAX_USBFS_BUFFER_SIZE René Rebe
2006-03-02 16:47         ` MAX_USBFS_BUFFER_SIZE Greg KH
2006-03-02 16:03       ` MAX_USBFS_BUFFER_SIZE René Rebe
2006-03-02 16:47         ` Greg KH [this message]
2006-03-01 21:59     ` MAX_USBFS_BUFFER_SIZE Duncan Sands
2006-03-03 10:34       ` MAX_USBFS_BUFFER_SIZE Oliver Neukum
     [not found]   ` <mailman.1141249502.22706.linux-kernel2news@redhat.com>
2006-03-02 21:05     ` MAX_USBFS_BUFFER_SIZE Pete Zaitcev
2006-03-03  7:27       ` MAX_USBFS_BUFFER_SIZE René Rebe
2006-03-03 20:32         ` MAX_USBFS_BUFFER_SIZE Greg KH
2006-03-03  8:12       ` MAX_USBFS_BUFFER_SIZE Duncan Sands
2006-03-03 10:29         ` MAX_USBFS_BUFFER_SIZE Oliver Neukum

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