Date: Mon, 14 Mar 2011 22:05:59 +0000 (UTC) From: Jung-uk Kim <jkim@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r219646 - head/sys/x86/isa Message-ID: <201103142205.p2EM5x6E012664@svn.freebsd.org>
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Author: jkim Date: Mon Mar 14 22:05:59 2011 New Revision: 219646 URL: http://svn.freebsd.org/changeset/base/219646 Log: When TSC is unavailable, broken or disabled and the current timecounter has better quality than i8254 timer, use it for DELAY(9). Modified: head/sys/x86/isa/clock.c Modified: head/sys/x86/isa/clock.c ============================================================================== --- head/sys/x86/isa/clock.c Mon Mar 14 19:31:43 2011 (r219645) +++ head/sys/x86/isa/clock.c Mon Mar 14 22:05:59 2011 (r219646) @@ -245,6 +245,42 @@ getit(void) return ((high << 8) | low); } +static __inline void +delay_tsc(int n) +{ + uint64_t start, end, now; + + sched_pin(); + start = rdtsc(); + end = start + (tsc_freq * n) / 1000000; + do { + cpu_spinwait(); + now = rdtsc(); + } while (now < end || (now > start && end < start)); + sched_unpin(); +} + +static __inline void +delay_timecounter(struct timecounter *tc, int n) +{ + uint64_t end, now; + u_int last, mask, u; + + mask = tc->tc_counter_mask; + last = tc->tc_get_timecount(tc) & mask; + end = tc->tc_frequency * n / 1000000; + now = 0; + do { + cpu_spinwait(); + u = tc->tc_get_timecount(tc) & mask; + if (u < last) + now += mask - last + u + 1; + else + now += u - last; + last = u; + } while (now < end); +} + /* * Wait "n" microseconds. * Relies on timer 1 counting down from (i8254_freq / hz) @@ -253,6 +289,7 @@ getit(void) void DELAY(int n) { + struct timecounter *tc; int delta, prev_tick, tick, ticks_left; #ifdef DELAYDEBUG @@ -262,16 +299,12 @@ DELAY(int n) #endif if (tsc_freq != 0) { - uint64_t start, end, now; - - sched_pin(); - start = rdtsc(); - end = start + (tsc_freq * n) / 1000000; - do { - cpu_spinwait(); - now = rdtsc(); - } while (now < end || (now > start && end < start)); - sched_unpin(); + delay_tsc(n); + return; + } + tc = timecounter; + if (tc->tc_quality > 0) { + delay_timecounter(tc, n); return; } #ifdef DELAYDEBUG
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