From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1O28QD-00078d-Rz for qemu-devel@nongnu.org; Wed, 14 Apr 2010 15:38:49 -0400 Received: from [140.186.70.92] (port=38881 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1O28QB-00077J-AT for qemu-devel@nongnu.org; Wed, 14 Apr 2010 15:38:49 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1O28Q6-0004Tb-MC for qemu-devel@nongnu.org; Wed, 14 Apr 2010 15:38:46 -0400 Received: from fmmailgate01.web.de ([217.72.192.221]:34921) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1O28Q6-0004T6-BZ for qemu-devel@nongnu.org; Wed, 14 Apr 2010 15:38:42 -0400 Message-ID: <4BC619C0.204@web.de> Date: Wed, 14 Apr 2010 21:38:40 +0200 From: Jan Kiszka MIME-Version: 1.0 Subject: Re: [Qemu-devel] Re: ehci update References: <4BC3F3FC.6050809@cisco.com> <4BC4FFC8.3060702@web.de> <4BC50337.8040201@cisco.com> <73AB16E6-5B01-4848-B8B7-895AEC5DAF76@suse.de> <4BC53816.8060401@cisco.com> In-Reply-To: <4BC53816.8060401@cisco.com> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig5126CCE26628A526CA5926A5" Sender: jan.kiszka@web.de List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "David S. Ahern" Cc: Alexander Graf , qemu-devel@nongnu.org This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig5126CCE26628A526CA5926A5 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable David S. Ahern wrote: >=20 > On 04/13/2010 07:20 PM, Alexander Graf wrote: >>>>> It still needs a lot of love, but definitely an improvement from th= e >>>>> last version. The biggest difference for the performance boost and >>>>> stability is discovering that the usbfs in linux limits transaction= s to >>>>> 16k versus the EHCI spec which allows 20k per qTD. I added a hack t= o >>>>> submit which detects 20k requests from a guest and breaks it up int= o 2 >>>>> requests through the host (a 16k and then a 4k). >>>> Did someone already bring this up on LKML or wherever usbfs is >>>> discussed? Should be fixable, I naively guess. >>> I submitted the patch to linux-usb and it was nack'ed. The response w= as >>> that memory is allocated in powers of 2 so trying to up the limit fro= m >>> 16k to 20k means it will actually want to find 32k of contiguous memo= ry. >>> The suggestion was to handle it with multiple requests within qemu. I= >>> guess libusb does that. >> Any reason we're not using libusb? >=20 > Good question. I was wondering the same. I was going to look at > converting usb-linux to use libusb1 when I get some time. Will that overcome the 16k limit or just push the split-up into libusb? Jan --------------enig5126CCE26628A526CA5926A5 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.9 (GNU/Linux) Comment: Using GnuPG with SUSE - http://enigmail.mozdev.org iEYEARECAAYFAkvGGcAACgkQitSsb3rl5xRzCgCaA6sFOpXb1ex81zHwcrvXM2R1 7BMAnjr0gi9iFoyFms4/vl/GSALRI3yE =7E+M -----END PGP SIGNATURE----- --------------enig5126CCE26628A526CA5926A5--