Date: Wed, 8 Jun 2016 13:56:47 +0200 From: Marko Zec <zec@fer.hr> To: "Bjoern A. Zeeb" <bz@freebsd.org> Cc: <src-committers@freebsd.org>, <svn-src-projects@freebsd.org> Subject: Re: svn commit: r301601 - projects/vnet/sys/netinet Message-ID: <20160608135647.52b3bdec@x23> In-Reply-To: <201606081124.u58BO1IH092140@repo.freebsd.org> References: <201606081124.u58BO1IH092140@repo.freebsd.org>
next in thread | previous in thread | raw e-mail | index | archive | help
On Wed, 8 Jun 2016 11:24:01 +0000 "Bjoern A. Zeeb" <bz@freebsd.org> wrote: > Author: bz > Date: Wed Jun 8 11:24:01 2016 > New Revision: 301601 > URL: https://svnweb.freebsd.org/changeset/base/301601 > > Log: > Replace the DELAY with a more sophisticated check to make sure > the inps are all gone before doing the cleanup. We might decide > to do a partial cleanup before polling, but for now bail on the > safe side. > > Also use pause instead of DELAY [1]. This is a welcome improvement! However, unconditionally pausing for 100 ms migt be an overpessimization here. Perhaps the pause could be moved after reading V_tcbinfo.ipi_count, in order to pause conditionally only on non-zero reads, which should almost never happen in practice, as the DELAY() hack was already deemed a safety belt in the first place. And even if / when the pause would be triggered, it would be probably enough to sleep for 10 ms or so - the removed DELAY() actually lasted for only a single clock tick. Marko > Suggested by: rwatson [1] > Sponsored by: The FreeBSD Foundation > > Modified: > projects/vnet/sys/netinet/tcp_subr.c > > Modified: projects/vnet/sys/netinet/tcp_subr.c > ============================================================================== > --- projects/vnet/sys/netinet/tcp_subr.c Wed Jun 8 11:18:49 > 2016 (r301600) +++ projects/vnet/sys/netinet/tcp_subr.c > Wed Jun 8 11:24:01 2016 (r301601) @@ -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?20160608135647.52b3bdec>