From mboxrd@z Thu Jan 1 00:00:00 1970 From: Leon Romanovsky Subject: Re: [PATCH 3/7] IB/srpt: Change default behavior from using SRQ to not using SRQ Date: Tue, 10 Oct 2017 18:00:18 +0300 Message-ID: <20171010150018.GC2106@mtr-leonro.local> References: <20171006214243.11296-1-bart.vanassche@wdc.com> <20171006214243.11296-4-bart.vanassche@wdc.com> <20171008100317.GR25829@mtr-leonro.local> <1507568205.46071.46.camel@redhat.com> <1507568492.2674.11.camel@wdc.com> <20171010041423.GJ1252@mtr-leonro.local> <9443ec1f-0acd-9fa3-4621-a29085d2c606@redhat.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="GPJrCs/72TxItFYR" Return-path: Content-Disposition: inline In-Reply-To: <9443ec1f-0acd-9fa3-4621-a29085d2c606-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Doug Ledford Cc: Bart Van Assche , "linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" List-Id: linux-rdma@vger.kernel.org --GPJrCs/72TxItFYR Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Tue, Oct 10, 2017 at 10:34:19AM -0400, Doug Ledford wrote: > On 10/10/2017 12:14 AM, Leon Romanovsky wrote: > > On Mon, Oct 09, 2017 at 05:01:33PM +0000, Bart Van Assche wrote: > >> On Mon, 2017-10-09 at 12:56 -0400, Doug Ledford wrote: > >>> On Sun, 2017-10-08 at 13:03 +0300, Leon Romanovsky wrote: > >>>> It is a little bit strange to ask from user to decide if his adapter > >>>> supports SRQ or not. > >>>> > >>>> It should be automatically. > >>> > >>> I think Bart's intent is that the driver not use SRQ as the default > >>> behavior even if the adapter supports it, so querying the adapter for > >>> support and enabling it if it exists would not achieve his desired > >>> result. This would then be used to override that behavior. Is that > >>> correct Bart? > >> > >> Hello Leon and Doug, > >> > >> The changes realized by this patch are: > >> - Instead of using SRQ as default, use non-SRQ mode as default. > >> - If SRQ has been chosen as default, and if SRQ is not supported, fall back > >> to non-SRQ mode (see also the if (IS_ERR(sdev->srq)) ... code). > >> > >> Please let me know if you have any further questions about this patch. > > > > Yes, in case HCA supports SRQ, when do you set that module parameter? > > You set it in your /etc/modprobe.d/ib_srp.conf file or the equivalent in > your OS. Doug, But my question was "when" and not "how". When should I set this parameter to true? > > > In the commit message, you mentioned disadvantages of using SRQ is a > > default and among them - locks contention, which can be changed in the > > future. Won't it mean that users stuck with current default, because > > change of default will "break" their scripts? > > No, it won't. If you change the default, you don't remove the variable, > you just change what its setting is. Then existing modprobe.d files > become redundant, but nothing breaks. People that don't want the new > setting add a new file to the modprobe.d directory to change the option. Not accurate, now I won't set any parameter because I'm relying on the fact that the default is without SRQ. Once the default will be changed, it will break my assumption. > > > Setting visible to user default won't allow us to change SRP behavior in > > the future. > > No it doesn't. > > > I wouldn't recommend to make such option accessible by users. > > > > Thanks > > > >> > >> Bart. > > > -- > Doug Ledford > GPG Key ID: B826A3330E572FDD > Key fingerprint = AE6B 1BDA 122B 23B4 265B 1274 B826 A333 0E57 2FDD > --GPJrCs/72TxItFYR Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEkhr/r4Op1/04yqaB5GN7iDZyWKcFAlnc4IIACgkQ5GN7iDZy WKelZg//Q0hPj7VPFJ0rv7I6pWOW2xXdqk5TiLLkTMimZvhazsQkb+TVSw5P7/rO dFFqjg+n+9ovYFVpa8e3FZR19ZvgKF6VPwYmwjCAqxLdUCnecbjZB5EwLL8FuPkO ZtX3rMnwGh9gDLbiVV9RPyrXgQ60qbdCfWEUdClF8/lTAj91mb2NO9Y8Eb2J/6+C hV4HddliHz32gIfXPQebKq/UUmuv0x6Z01KrgLf/zFAp3XNTSsDbHO8o9rfanE9K VJJ61QLHyR8pQEvij8eJs1BfJgFEDcD8VjHVA8mFfJVi1AVT6i/mURBF/VP/tOHf Wux/wbnPyvgk4Yyx2sxrHppqxct0rAR/4ch9wyYC3qDs2u2kPnvXN63Mk+iW/9Lu 8R/3hvPQuFTRJYqkI700301+W9IBCNJkZylGIpB2SB3TPOHrggvUtH8Oq+9jU2pk sKDZqO+2GUPQ+AWQJjYycBrc6B6UxDUJSMoCXVd5pPDshlqp7hXC5EZqdOYDLA7N 2sJqvypCUrEXNaKYo6YKUdHZdA0I/5VBEz/Acc77Cczp2erYvJ7E3VhmHZQJ5xIZ xAlJ5av+fyUmT+O4/MOU+OyyAEXHZodE58UKqbqAMz5CSYeDwXm3qS/XfgZ4c6dE NlxXUjQA/lJafD5a8vjiaY8ECeGQJiOO+f3VxxjL/96NU9Oz4G4= =vclc -----END PGP SIGNATURE----- --GPJrCs/72TxItFYR-- -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html