Date: Thu, 23 Jun 2016 10:17:57 +0200 From: Marko Zec <zec@fer.hr> To: "Bjoern A. Zeeb" <bz@freebsd.org> Cc: <src-committers@freebsd.org>, <svn-src-all@freebsd.org>, <svn-src-head@freebsd.org>, <gnn@freebsd.org>, <jtl@freebsd.org>, <gjb@freebsd.org> Subject: Re: svn commit: r302099 - head/sys/netinet Message-ID: <20160623101757.3e8022fe@x23> In-Reply-To: <201606230034.u5N0Y3Ea069103@repo.freebsd.org> References: <201606230034.u5N0Y3Ea069103@repo.freebsd.org>
next in thread | previous in thread | raw e-mail | index | archive | help
On Thu, 23 Jun 2016 00:34:03 +0000 "Bjoern A. Zeeb" <bz@freebsd.org> wrote: > Author: bz > Date: Thu Jun 23 00:34:03 2016 > New Revision: 302099 > URL: https://svnweb.freebsd.org/changeset/base/302099 > > Log: > Check the V_tcbinfo.ipi_count to hit 0 before doing the full TCP > cleanup. That way timers can finish cleanly and we do not gamble with > a DELAY(). > Reviewed by: gnn, jtl > Approved by: re (gjb) > Obtained from: projects/vnet > MFC after: 2 weeks > Sponsored by: The FreeBSD Foundation > Differential Revision: https://reviews.freebsd.org/D6923 As much as this change is welcome, it unnecesarily introduces a mandatory 100 ms delay on each vnet teardown, which I already pointed out in a comment to r301601 two weeks ago, which remained unanswered, along with the question why a delay of 100 ms was introduced here, when before r302099 the delay was only a single clock tick? And furthermore the delay computation expresion here is not style(9) compliant... Hence, please rectify the above objections, perhaps by something like: =================================================================== --- tcp_subr.c (revision 302126) +++ tcp_subr.c (working copy) @@ -739,10 +739,11 @@ * Sleep to let all tcpcb timers really disappear and cleanup. */ do { - pause("tcpdes", hz/10); INP_LIST_RLOCK(&V_tcbinfo); n = V_tcbinfo.ipi_count; INP_LIST_RUNLOCK(&V_tcbinfo); + if (n != 0) + pause("tcpdes", hz / 100); } while (n != 0); tcp_hc_destroy(); syncache_destroy(); Thanks, Marko > > Modified: > head/sys/netinet/tcp_subr.c > > Modified: head/sys/netinet/tcp_subr.c > ============================================================================== > --- head/sys/netinet/tcp_subr.c Thu Jun 23 00:32:58 > 2016 (r302098) +++ head/sys/netinet/tcp_subr.c Thu Jun > 23 00:34:03 2016 (r302099) @@ -731,18 +731,19 @@ tcp_init(void) > static void > tcp_destroy(void *unused __unused) > { > - int error; > + int error, n; > > /* > * All our processes are gone, all our sockets should be > cleaned > * up, which means, we should be past the tcp_discardcb() > calls. > - * Sleep to let all tcpcb timers really disappear and then > cleanup. > - * Timewait will cleanup its queue and will be ready to go. > - * XXX-BZ In theory a few ticks should be good enough to > make sure > - * the timers are all really gone. We should see if we > could use a > - * better metric here and, e.g., check a tcbcb count as an > optimization? > + * Sleep to let all tcpcb timers really disappear and > cleanup. */ > - DELAY(1000000 / hz); > + do { > + pause("tcpdes", hz/10); > + INP_LIST_RLOCK(&V_tcbinfo); > + n = V_tcbinfo.ipi_count; > + INP_LIST_RUNLOCK(&V_tcbinfo); > + } while (n != 0); > tcp_hc_destroy(); > syncache_destroy(); > tcp_tw_destroy(); >
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20160623101757.3e8022fe>