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Reduce periods of simultaneous acquisition of various socket buffer

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locks and the unplock during uipc_rcvd() and uipc_send() by caching
certain values from one structure while its locks are held, and
applying them to a second structure while its locks are held.  If
done carefully, this should be correct, and will reduce the amount
of work done with the global unp lock held.

Tested by:	kris (earlier version)
This commit is contained in:
Robert Watson 2006-07-11 21:49:54 +00:00
parent 90aff9de2d
commit 337cc6b60e
1 changed files with 28 additions and 20 deletions
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48
sys/kern/uipc_usrreq.c
View File

@ -299,41 +299,45 @@ uipc_rcvd(struct socket *so, int flags)
{
struct unpcb *unp;
struct socket *so2;
u_int mbcnt, sbcc;
u_long newhiwat;
unp = sotounpcb(so);
KASSERT(unp != NULL, ("uipc_rcvd: unp == NULL"));
UNP_LOCK();
switch (so->so_type) {
case SOCK_DGRAM:
panic("uipc_rcvd DGRAM?");
/*NOTREACHED*/
case SOCK_STREAM:
if (unp->unp_conn == NULL)
break;
so2 = unp->unp_conn->unp_socket;
SOCKBUF_LOCK(&so2->so_snd);
SOCKBUF_LOCK(&so->so_rcv);
/*
* Adjust backpressure on sender
* and wakeup any waiting to write.
*/
so2->so_snd.sb_mbmax += unp->unp_mbcnt - so->so_rcv.sb_mbcnt;
unp->unp_mbcnt = so->so_rcv.sb_mbcnt;
newhiwat = so2->so_snd.sb_hiwat + unp->unp_cc -
so->so_rcv.sb_cc;
SOCKBUF_LOCK(&so->so_rcv);
mbcnt = so->so_rcv.sb_mbcnt;
sbcc = so->so_rcv.sb_cc;
SOCKBUF_UNLOCK(&so->so_rcv);
UNP_LOCK();
if (unp->unp_conn == NULL) {
UNP_UNLOCK();
break;
}
so2 = unp->unp_conn->unp_socket;
SOCKBUF_LOCK(&so2->so_snd);
so2->so_snd.sb_mbmax += unp->unp_mbcnt - mbcnt;
newhiwat = so2->so_snd.sb_hiwat + unp->unp_cc - sbcc;
(void)chgsbsize(so2->so_cred->cr_uidinfo, &so2->so_snd.sb_hiwat,
newhiwat, RLIM_INFINITY);
unp->unp_cc = so->so_rcv.sb_cc;
SOCKBUF_UNLOCK(&so->so_rcv);
sowwakeup_locked(so2);
unp->unp_mbcnt = mbcnt;
unp->unp_cc = sbcc;
UNP_UNLOCK();
break;
default:
panic("uipc_rcvd unknown socktype");
}
UNP_UNLOCK();
return (0);
}
@ -346,6 +350,7 @@ uipc_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *nam,
int error = 0;
struct unpcb *unp;
struct socket *so2;
u_int mbcnt, sbcc;
u_long newhiwat;
unp = sotounpcb(so);
@ -416,9 +421,8 @@ uipc_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *nam,
}
}
SOCKBUF_LOCK(&so->so_snd);
/* Lockless read. */
if (so->so_snd.sb_state & SBS_CANTSENDMORE) {
SOCKBUF_UNLOCK(&so->so_snd);
error = EPIPE;
break;
}
@ -445,16 +449,20 @@ uipc_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *nam,
} else {
sbappend_locked(&so2->so_rcv, m);
}
so->so_snd.sb_mbmax -=
so2->so_rcv.sb_mbcnt - unp->unp_conn->unp_mbcnt;
mbcnt = so2->so_rcv.sb_mbcnt - unp->unp_conn->unp_mbcnt;
unp->unp_conn->unp_mbcnt = so2->so_rcv.sb_mbcnt;
sbcc = so2->so_rcv.sb_cc;
sorwakeup_locked(so2);
SOCKBUF_LOCK(&so->so_snd);
newhiwat = so->so_snd.sb_hiwat -
(so2->so_rcv.sb_cc - unp->unp_conn->unp_cc);
(sbcc - unp->unp_conn->unp_cc);
(void)chgsbsize(so->so_cred->cr_uidinfo, &so->so_snd.sb_hiwat,
newhiwat, RLIM_INFINITY);
so->so_snd.sb_mbmax -= mbcnt;
SOCKBUF_UNLOCK(&so->so_snd);
unp->unp_conn->unp_cc = so2->so_rcv.sb_cc;
sorwakeup_locked(so2);
unp->unp_conn->unp_cc = sbcc;
m = NULL;
break;