Date: Fri, 8 May 2009 21:44:20 GMT From: Marko Zec <zec@FreeBSD.org> To: Perforce Change Reviews <perforce@freebsd.org> Subject: PERFORCE change 161793 for review Message-ID: <200905082144.n48LiKYP021818@repoman.freebsd.org>
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http://perforce.freebsd.org/chv.cgi?CH=161793 Change 161793 by zec@zec_tpx32 on 2009/05/08 21:43:51 A controversial hack: when allocating if_unit numbers for cloning ifnets, do NOT resort to bitmap mappings, but iterate through all existing ifnets in a particular vnet as long as a free unit number is found. The problem here is that we are switchng from a O(n) to a O(n**2) search method with more work being done in each iteration. So this should be revisited RSN. Affected files ... .. //depot/projects/vimage-commit2/src/sys/net/if_clone.c#5 edit Differences ... ==== //depot/projects/vimage-commit2/src/sys/net/if_clone.c#5 (text+ko) ==== @@ -401,6 +401,25 @@ * Find a free unit if none was given. */ if (wildcard) { +#ifdef VIMAGE + /* XXX revisit - O(n**2) loop bellow! */ + INIT_VNET_NET(curvnet); + char name[IFNAMSIZ]; + struct ifnet *ifp; + int i = 0; + + IFNET_RLOCK(); +again: + TAILQ_FOREACH(ifp, &V_ifnet, if_link) { + sprintf(name, "%s%d", ifc->ifc_name, i); + if (strcmp(name, ifp->if_xname) == 0) { + i++; + goto again; + } + } + IFNET_RUNLOCK(); + *unit = i; +#else while ((bytoff < ifc->ifc_bmlen) && (ifc->ifc_units[bytoff] == 0xff)) bytoff++; @@ -411,6 +430,7 @@ while ((ifc->ifc_units[bytoff] & (1 << bitoff)) != 0) bitoff++; *unit = (bytoff << 3) + bitoff; +#endif } if (*unit > ifc->ifc_maxunit) { @@ -418,6 +438,7 @@ goto done; } +#ifndef VIMAGE if (!wildcard) { bytoff = *unit >> 3; bitoff = *unit - (bytoff << 3); @@ -433,6 +454,7 @@ KASSERT((ifc->ifc_units[bytoff] & (1 << bitoff)) == 0, ("%s: bit is already set", __func__)); ifc->ifc_units[bytoff] |= (1 << bitoff); +#endif IF_CLONE_ADDREF_LOCKED(ifc); done: @@ -443,19 +465,22 @@ void ifc_free_unit(struct if_clone *ifc, int unit) { +#ifndef VIMAGE int bytoff, bitoff; - /* * Compute offset in the bitmap and deallocate the unit. */ bytoff = unit >> 3; bitoff = unit - (bytoff << 3); +#endif IF_CLONE_LOCK(ifc); +#ifndef VIMAGE KASSERT((ifc->ifc_units[bytoff] & (1 << bitoff)) != 0, ("%s: bit is already cleared", __func__)); ifc->ifc_units[bytoff] &= ~(1 << bitoff); +#endif IF_CLONE_REMREF_LOCKED(ifc); /* releases lock */ }help
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