From mboxrd@z Thu Jan 1 00:00:00 1970 From: Leon Romanovsky Subject: Re: [PATCH] ib_core: Enable and expose force_mr module parameter Date: Mon, 15 May 2017 20:00:21 +0300 Message-ID: <20170515170021.GJ3616@mtr-leonro.local> References: <20170515145203.10708.16921.stgit@klimt.1015granger.net> <20170515145757.GI3616@mtr-leonro.local> <02AFF424-A387-47F7-BD24-61C7734B9008@oracle.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="GrZJL/A7LJaW37J8" Return-path: Content-Disposition: inline In-Reply-To: <02AFF424-A387-47F7-BD24-61C7734B9008-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Chuck Lever Cc: linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-rdma@vger.kernel.org --GrZJL/A7LJaW37J8 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Mon, May 15, 2017 at 11:09:06AM -0400, Chuck Lever wrote: > > > On May 15, 2017, at 10:57 AM, Leon Romanovsky wrote: > > > > On Mon, May 15, 2017 at 10:52:44AM -0400, Chuck Lever wrote: > >> The fourth parameter of the module_param_named macro is a set of > >> file permissions. Passing 0 there means that module parameter is > >> not created and that adding "options ib_core force_mr=1" to a > >> modprobe.conf file has no effect. > >> > >> The default setting of rdma_rw_force_mr continues to be 0, or false. > >> > >> Fixes: a060b5629ab0 ("IB/core: generic RDMA READ/WRITE API") > >> Signed-off-by: Chuck Lever > > > > Chuck, > > > > Do we really need this parameter? > > Hi Leon- > > Christoph and Sagi introduced this with the new rdma_rw API. > The default behavior is to avoid the use of FRWR, even for > devices that can support FRWR but also work without. FRWR is > used only for iWARP devices, which require it; but FRWR can > have a (slight) negative performance impact, which is why it > is not the default. > > The purpose of this module parameter is to enable the use of > FRWR for devices that can go either way, as a way to test the > FRWR capability when using those devices. > > I'm not sure we _need_ to have the module parameter. But I've > certainly used it while developing the NFSD conversion to use > the rdma_rw API, since I have no iWARP devices here. I asked that question because commit a060b5629ab0 was added a year ago and since then no one noticed that it is not usable, including authors. I think that we can safely remove it and for development, we can set rdma_rw_force_mr internally in the code. Thanks > > > >> --- > >> drivers/infiniband/core/rw.c | 2 +- > >> 1 file changed, 1 insertion(+), 1 deletion(-) > >> > >> diff --git a/drivers/infiniband/core/rw.c b/drivers/infiniband/core/rw.c > >> index dbfd854..1cc8f07 100644 > >> --- a/drivers/infiniband/core/rw.c > >> +++ b/drivers/infiniband/core/rw.c > >> @@ -23,7 +23,7 @@ enum { > >> }; > >> > >> static bool rdma_rw_force_mr; > >> -module_param_named(force_mr, rdma_rw_force_mr, bool, 0); > >> +module_param_named(force_mr, rdma_rw_force_mr, bool, 0644); > >> MODULE_PARM_DESC(force_mr, "Force usage of MRs for RDMA READ/WRITE operations"); > >> > >> /* > >> > >> -- > >> 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 > > -- > Chuck Lever > > > > -- > 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 --GrZJL/A7LJaW37J8 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEkhr/r4Op1/04yqaB5GN7iDZyWKcFAlkZ3qUACgkQ5GN7iDZy WKecrg/9G3imSAb4dpPk8CNsuXfk9SRG5mlAIVKyOdm5C9GeepOZNXTLWk0sPXVI MgGU5fe4M+nWVlQwxNFYXlNzQEXcL7L4zhHL7lCgWoM4GfuvKHua2DJIDbY2zu1w n5zMtcmVSokc9Bhk07GbwmKJowBCcHiZIbZDHf/vu3fCfNBI+yTiDu2Ev0EGWWuP 4dVOjDHjedq5CAHPjwrRFTvtsjv4PZRV5e0RxnKau3aZCXuTKTYoflEWdPJ74QDO yzA58Z1EmDKlcvH1tAey3pbIjmzv7jrVkTMfzhDVr1lMsGiGcJ//jUGEtyPMWuQ4 7DHAavdDyY8FuvGLKwudD076ce/+Ihrnhitr35+lYMJv9R9pcD/4GkfbCfksumcO W7fmbdN/1TG3u9vHE/1sp0ajPELj+x0QJjKEInHQuBFae4W6GnelbHZvXxc+dEUi bP3XhQP/HN/AbzmO6q5LtDVz1+k7p7PbpBX3fll129mrruCngYXIerTvPzPOeWrh LBjeln+lZx6k6pwEmUn3nOeY0Y9tnj8w+TI0mUVLxsPNm9vA7Ycgkr2ofAFCk156 bMDXY6I/QZ0mach6XnkqJi1SZgEitZcx3i7G3FF0B5CPJGO7du4HwVvrz24OtGYU ObHv5Yqsq2Q6zJ05JzHCj1X47cu8hXBSM/ec6MqUFeCQGdQC27c= =xYa8 -----END PGP SIGNATURE----- --GrZJL/A7LJaW37J8-- -- 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