From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sasha Khapyorsky Subject: Re: [PATCH v2] opensm: Multicast root switch calculation Date: Wed, 20 Jan 2010 13:59:36 +0200 Message-ID: <20100120115936.GC25576@me> References: <4B17C712.9010109@Voltaire.COM> <20100120102703.GB25576@me> <39C75744D164D948A170E9792AF8E7CA01F6FA8A@exil.voltaire.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <39C75744D164D948A170E9792AF8E7CA01F6FA8A-QfUkFaTmzUSUvQqKE/ONIwC/G2K4zDHf@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Slava Strebkov Cc: linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Eli Dorfman , Or Gerlitz , Yevgeny Kliteynik List-Id: linux-rdma@vger.kernel.org On 13:32 Wed 20 Jan , Slava Strebkov wrote: > "average hops" was chosen instead of "max hops" because in root weight > calculation the number of ports is also important, not only the distance > (hops). But this patch is declared as root switch calculation optimization, not as algorithm change (actually I even missed this part in V1). If you think that an algorithm should be changed we need to handle this separately. And there could be a discussion - I have report that some days ago credit loop issue was observed when "average hops" method was used (and then it was replaced by "max hops"). I don't have much details about this case and cannot be sure that it was not "false alarm" (or outdated information), but anyway I think that we should be careful here. Sasha > -----Original Message----- > From: Sasha Khapyorsky [mailto:sashakvolt-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org] On Behalf Of Sasha > Khapyorsky > Sent: Wednesday, January 20, 2010 12:27 PM > To: Slava Strebkov > Cc: linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; Eli Dorfman; Or Gerlitz; Yevgeny > Kliteynik > Subject: Re: [PATCH v2] opensm: Multicast root switch calculation > > Hi Slava, > > On 16:11 Thu 03 Dec , Slava Strebkov wrote: > > Proposed new algorithm for calculation of root switch for multicast > > spanning tree. Only edge switches(those connected to hosts) and > > switches - multicast members themselves are involved in root > calculation. > > This gives improvement, especially on large fabrics, since number of > > switches usually much less then the number of ports, shared same mcast > > group. > > > > Signed-off-by: Slava Strebkov > > --- > > [snip] > > > @@ -231,32 +342,27 @@ static float > osm_mcast_mgr_compute_max_hops(osm_sm_t * sm, cl_qlist_t * l, > > of the multicast group. > > > **********************************************************************/ > > static osm_switch_t *mcast_mgr_find_optimal_switch(osm_sm_t * sm, > > - cl_qlist_t *list) > > + cl_qlist_t * list) > > { > > cl_qmap_t *p_sw_tbl; > > osm_switch_t *p_sw, *p_best_sw = NULL; > > float hops = 0; > > float best_hops = 10000; /* any big # will do */ > > -#ifdef OSM_VENDOR_INTF_ANAFA > > - boolean_t use_avg_hops = TRUE; /* anafa2 - bug hca on switch > *//* use max hops for root */ > > -#else > > - boolean_t use_avg_hops = FALSE; /* use max hops for root */ > > -#endif > > - > > + cl_qmap_t mcast_member_sw_tbl; > > OSM_LOG_ENTER(sm->p_log); > > > > p_sw_tbl = &sm->p_subn->sw_guid_tbl; > > > > + mcast_mgr_build_switch_map(sm, list, &mcast_member_sw_tbl); > > for (p_sw = (osm_switch_t *) cl_qmap_head(p_sw_tbl); > > p_sw != (osm_switch_t *) cl_qmap_end(p_sw_tbl); > > p_sw = (osm_switch_t *) cl_qmap_next(&p_sw->map_item)) { > > if (!osm_switch_supports_mcast(p_sw)) > > continue; > > > > - if (use_avg_hops) > > - hops = osm_mcast_mgr_compute_avg_hops(sm, list, > p_sw); > > - else > > - hops = osm_mcast_mgr_compute_max_hops(sm, list, > p_sw); > > + hops = > > + osm_mcast_mgr_compute_avg_hops_weight(sm, p_sw, > > + > &mcast_member_sw_tbl); > > Any reason why was root switch computation method changed? By default it > was "max hops" based and as far as I can see you changed this to > "average hops". > > Sasha > > > > > OSM_LOG(sm->p_log, OSM_LOG_DEBUG, > > "Switch 0x%016" PRIx64 ", hops = %f\n", > > @@ -277,6 +383,7 @@ static osm_switch_t > *mcast_mgr_find_optimal_switch(osm_sm_t * sm, > > OSM_LOG(sm->p_log, OSM_LOG_VERBOSE, > > "No multicast capable switches detected\n"); > > > > + mcast_mgr_destroy_switch_map(sm, &mcast_member_sw_tbl); > > OSM_LOG_EXIT(sm->p_log); > > return p_best_sw; > > } > > -- > > 1.6.3.3 > > > > -- > > 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 > > > -- 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