From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga09.intel.com ([134.134.136.24]:7941 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750970AbcKCKml (ORCPT ); Thu, 3 Nov 2016 06:42:41 -0400 From: Felipe Balbi To: Peter Chen Cc: David Miller , linux-usb@vger.kernel.org, ville.syrjala@linux.intel.com, stable@vger.kernel.org Subject: Re: [PATCH] usb: gadget: u_ether: remove interrupt throttling In-Reply-To: <20161103090310.GC894@b29397-desktop> References: <20161101112959.19640-1-felipe.balbi@linux.intel.com> <20161102060202.GD28525@b29397-desktop> <20161102.112254.1243059410485662386.davem@davemloft.net> <20161103002300.GA894@b29397-desktop> <87wpglqc15.fsf@linux.intel.com> <20161103090310.GC894@b29397-desktop> Date: Thu, 03 Nov 2016 12:42:11 +0200 Message-ID: <87lgx0n8u4.fsf@linux.intel.com> MIME-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha256; protocol="application/pgp-signature" Sender: stable-owner@vger.kernel.org List-ID: --=-=-= Content-Type: text/plain Content-Transfer-Encoding: quoted-printable Hi, Peter Chen writes: >> Peter Chen writes: >> > On Wed, Nov 02, 2016 at 11:22:54AM -0400, David Miller wrote: >> >> From: Peter Chen >> >> Date: Wed, 2 Nov 2016 14:02:02 +0800 >> >>=20 >> >> > Felipe, it may increase cpu utilization since more interrupts will = be there, >> >> > it may affect the SoC which has lower cpu frequency. This code exis= ted >> >> > many years, why this problem has only reported at dwc3 recently? >> >>=20 >> >> It's a bug, and it's going to cause TCP sockets to potentially hang. >> >>=20 >> > >> > For some controllers, it is, so we need to add parameter for user >> > to see if interrupt migration is supported or not. >>=20 >> not for some controller, for ALL networking drivers. >>=20 >> > But just like some ethernet controllers, some USB controllers support >> > hardware timeout mechanism which interrupt will be triggered after >> > some uFrame occurs if the transaction has completed but not required >> > to interrupt, it is used to support interrupt migration like ethernet. >>=20 >> you're missing the point. What Dave Miller is saying is that it's ALWAYS >> a bug to delay completion of SKBs. The only thing you're doing with >> chipidea is delaying interrupt by up to 125us; which is still a bug from >> the point of view of the networking layer, but it's more difficult to >> perceive any problems because of the short time where interrupt is >> delayed. >>=20 > > If it is ALWAYS a bug to delay completion of SKBs, how the local > ethernet driver designs interrupt migration? what driver are you talking about? Which "local" ethernet driver? Also, do you mean 'moderation' instead of 'migration? =2D-=20 balbi --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIcBAEBCAAGBQJYGxSDAAoJEMy+uJnhGpkGQ9EP/2KcgsIGt+uO0a0GNFR3ouHc olnae1iZ8b5LXjh+kj9FNXWTXJ52dwSWa0E2Kp+c3IZnXUZxpUhYRjbDknd57pKY AQIROiQWIEoZXvNp3QZ7iShUNmGEseQJ+nSvng9UCjsVvgg+JTXurTZUEFMyVPV7 91mNoOhSuC2EinI9cVdsKaUHsvzZUe0g03B4m/2dQlH5D/DaWljLbUanP4naA1YO 9v8/rqxoShZCy6L5u4SKQkluRHLMei5jqdMHk4rVJIYEeS/S0kRPNhUulIP5m4nJ ZAOnY/bgQ0BPXtvjmPzcv6Eh9rvImJUGbL3PnrU/NrwDqYLMWyuDbI6Yh4joKppQ V7QZDvLLTHEhAN2RO4PIiBO9194Id5MScNMQqD5O+7VrAul6HF9d0HiEPpegfUDh 5iZL4GojdQv2Qgy2wU4bxG9YqFEaC5XLwuaKBOGsep1MmaPQqZ/+1TQi2Bzdq/cJ 6JKAkLYhJ+WrEVKYbRPJSkGqF1lOQMCcXqLwIzWOyaMLqOewOiYox11dKIJpsV0Y 0eTOMIRfnRWM9ciqlZsmcYm3DE66TtkayQJlY9Kj3iEgwhhiHB7CJBYd4IE7zQgW hmWLFBy99ti+Q4U6bUW/sNs9F4EWrpUD3OXEdKFLLPHO+xjn+8mMHSapR181N0X6 Vh02n6vAZeo2m85DDpVD =69al -----END PGP SIGNATURE----- --=-=-=--