diff options
Diffstat (limited to 'usr/src/uts/common/io/devpoll.c')
| -rw-r--r-- | usr/src/uts/common/io/devpoll.c | 69 |
1 files changed, 34 insertions, 35 deletions
diff --git a/usr/src/uts/common/io/devpoll.c b/usr/src/uts/common/io/devpoll.c index 09b21abf66..111c4c243f 100644 --- a/usr/src/uts/common/io/devpoll.c +++ b/usr/src/uts/common/io/devpoll.c @@ -23,6 +23,7 @@ * Use is subject to license terms. */ +/* Copyright (c) 2011 by Delphix. All rights reserved. */ #include <sys/types.h> #include <sys/devops.h> @@ -46,7 +47,7 @@ #define RESERVED 1 /* local data struct */ -static dp_entry_t **devpolltbl; /* dev poll entries */ +static dp_entry_t **devpolltbl; /* dev poll entries */ static size_t dptblsize; static kmutex_t devpoll_lock; /* lock protecting dev tbl */ @@ -238,7 +239,7 @@ dp_pcache_poll(pollfd_t *pfdp, pollcache_t *pcp, nfds_t nfds, int *fdcntp) { int start, ostart, end; int fdcnt, fd; - boolean_t done; + boolean_t done; file_t *fp; short revent; boolean_t no_wrap; @@ -492,7 +493,7 @@ dpopen(dev_t *devp, int flag, int otyp, cred_t *credp) static int dpwrite(dev_t dev, struct uio *uiop, cred_t *credp) { - minor_t minor; + minor_t minor; dp_entry_t *dpep; pollcache_t *pcp; pollfd_t *pollfdp, *pfdp; @@ -691,21 +692,12 @@ dpwrite(dev_t dev, struct uio *uiop, cred_t *credp) static int dpioctl(dev_t dev, int cmd, intptr_t arg, int mode, cred_t *credp, int *rvalp) { - timestruc_t now; - timestruc_t rqtime; - timestruc_t *rqtp = NULL; - int timecheck = 0; - minor_t minor; + minor_t minor; dp_entry_t *dpep; pollcache_t *pcp; - int error = 0; + int error = 0; STRUCT_DECL(dvpoll, dvpoll); - if (cmd == DP_POLL) { - /* do this now, before we sleep on DP_WRITER_PRESENT below */ - timecheck = timechanged; - gethrestime(&now); - } minor = getminor(dev); mutex_enter(&devpoll_lock); ASSERT(minor < dptblsize); @@ -730,11 +722,12 @@ dpioctl(dev_t dev, int cmd, intptr_t arg, int mode, cred_t *credp, int *rvalp) switch (cmd) { case DP_POLL: { - pollstate_t *ps; - nfds_t nfds; - int fdcnt = 0; - int time_out; - int rval; + pollstate_t *ps; + nfds_t nfds; + int fdcnt = 0; + int time_out; + clock_t *deltap = NULL; + clock_t delta; STRUCT_INIT(dvpoll, mode); error = copyin((caddr_t)arg, STRUCT_BUF(dvpoll), @@ -747,12 +740,15 @@ dpioctl(dev_t dev, int cmd, intptr_t arg, int mode, cred_t *credp, int *rvalp) time_out = STRUCT_FGET(dvpoll, dp_timeout); if (time_out > 0) { /* - * Determine the future time of the requested timeout. + * cv_relwaituntil_sig operates at the tick + * granularity, which by default is 10 ms. + * This results in rounding user specified + * timeouts up but prevents the system + * from being flooded with small high + * resolution timers. */ - rqtp = &rqtime; - rqtp->tv_sec = time_out / MILLISEC; - rqtp->tv_nsec = (time_out % MILLISEC) * MICROSEC; - timespecadd(rqtp, &now); + delta = MSEC_TO_TICK_ROUNDUP(time_out); + deltap = δ } if ((nfds = STRUCT_FGET(dvpoll, dp_nfds)) == 0) { @@ -765,17 +761,19 @@ dpioctl(dev_t dev, int cmd, intptr_t arg, int mode, cred_t *credp, int *rvalp) if (time_out == 0) return (0); mutex_enter(&curthread->t_delay_lock); - while ((rval = cv_waituntil_sig(&curthread->t_delay_cv, - &curthread->t_delay_lock, rqtp, timecheck)) > 0) + while ((delta = cv_relwaituntil_sig( + &curthread->t_delay_cv, &curthread->t_delay_lock, + deltap, TR_MILLISEC)) > 0) { continue; + } mutex_exit(&curthread->t_delay_lock); - return ((rval == 0)? EINTR : 0); + return (delta == 0 ? EINTR : 0); } /* - * XXX It'd be nice not to have to alloc each time. - * But it requires another per thread structure hook. - * Do it later if there is data suggest that. + * XXX It would be nice not to have to alloc each time, but it + * requires another per thread structure hook. This can be + * implemented later if data suggests that it's necessary. */ if ((ps = curthread->t_pollstate) == NULL) { curthread->t_pollstate = pollstate_create(); @@ -820,14 +818,15 @@ dpioctl(dev_t dev, int cmd, intptr_t arg, int mode, cred_t *credp, int *rvalp) */ if (time_out == 0) /* immediate timeout */ break; - rval = cv_waituntil_sig(&pcp->pc_cv, &pcp->pc_lock, - rqtp, timecheck); + + delta = cv_relwaituntil_sig(&pcp->pc_cv, &pcp->pc_lock, + deltap, TR_MILLISEC); /* * If we were awakened by a signal or timeout * then break the loop, else poll again. */ - if (rval <= 0) { - if (rval == 0) /* signal */ + if (delta <= 0) { + if (delta == 0) /* signal */ error = EINTR; break; } @@ -915,7 +914,7 @@ dppoll(dev_t dev, short events, int anyyet, short *reventsp, static int dpclose(dev_t dev, int flag, int otyp, cred_t *credp) { - minor_t minor; + minor_t minor; dp_entry_t *dpep; pollcache_t *pcp; int i; |