03b31bd3fb4f7ec9a4fa1d6e950d36d3a42396ef
2 * Copyright (c) 2012 ARM Limited
5 * The license below extends only to copyright in the software and shall
6 * not be construed as granting a license to any other intellectual
7 * property including but not limited to intellectual property relating
8 * to a hardware implementation of the functionality of the software
9 * licensed hereunder. You may use the software subject to the license
10 * terms below provided that you ensure that this notice is replicated
11 * unmodified and in its entirety in all distributions of the software,
12 * modified or unmodified, in source code or in binary form.
14 * Redistribution and use in source and binary forms, with or without
15 * modification, are permitted provided that the following conditions are
16 * met: redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer;
18 * redistributions in binary form must reproduce the above copyright
19 * notice, this list of conditions and the following disclaimer in the
20 * documentation and/or other materials provided with the distribution;
21 * neither the name of the copyright holders nor the names of its
22 * contributors may be used to endorse or promote products derived from
23 * this software without specific prior written permission.
25 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
26 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
27 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
28 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
29 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
30 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
31 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
32 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
33 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
34 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
35 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
37 * Authors: Andreas Sandberg
40 #include "cpu/kvm/timer.hh"
42 #include <sys/syscall.h>
49 #include "base/misc.hh"
50 #include "base/trace.hh"
51 #include "debug/KvmTimer.hh"
53 /* According to timer_create(2), the value SIGEV_THREAD_ID can be used
54 * to specify which thread a timer signal gets delivered to. According
55 * to the man page, the member sigev_notify_thread is used to specify
56 * the TID. This member is currently not defined by default in
57 * siginfo.h on x86, so we define it here as a workaround.
59 #ifndef sigev_notify_thread_id
60 #define sigev_notify_thread_id _sigev_un._tid
66 return syscall(__NR_gettid
);
70 * Minimum number of cycles that a host can spend in a KVM call (used
71 * to calculate the resolution of some timers).
73 * The value of this constant is a bit arbitrary, but in practice, we
74 * can't really do anything useful in less than ~1000 cycles.
76 static const uint64_t MIN_HOST_CYCLES
= 1000;
78 PosixKvmTimer::PosixKvmTimer(int signo
, clockid_t clockID
,
79 float hostFactor
, Tick hostFreq
)
80 : BaseKvmTimer(signo
, hostFactor
, hostFreq
),
85 sev
.sigev_notify
= SIGEV_THREAD_ID
;
86 sev
.sigev_signo
= signo
;
87 sev
.sigev_notify_thread_id
= gettid();
88 sev
.sigev_value
.sival_ptr
= NULL
;
90 while (timer_create(clockID
, &sev
, &timer
) == -1) {
92 panic("timer_create: %i", errno
);
96 PosixKvmTimer::~PosixKvmTimer()
102 PosixKvmTimer::arm(Tick ticks
)
104 struct itimerspec ts
;
105 memset(&ts
, 0, sizeof(ts
));
107 ts
.it_interval
.tv_sec
= 0;
108 ts
.it_interval
.tv_nsec
= 0;
109 ts
.it_value
.tv_sec
= hostNs(ticks
) / 1000000000ULL;
110 ts
.it_value
.tv_nsec
= hostNs(ticks
) % 1000000000ULL;
112 assert(ts
.it_value
.tv_nsec
> 0 || ts
.it_value
.tv_sec
> 0);
114 DPRINTF(KvmTimer
, "Arming POSIX timer: %i ticks (%is%ins)\n",
115 ticks
, ts
.it_value
.tv_sec
, ts
.it_value
.tv_nsec
);
117 if (timer_settime(timer
, 0, &ts
, NULL
) == -1)
118 panic("PosixKvmTimer: Failed to arm timer\n");
122 PosixKvmTimer::disarm()
124 struct itimerspec ts
;
125 memset(&ts
, 0, sizeof(ts
));
127 DPRINTF(KvmTimer
, "Disarming POSIX timer\n");
129 if (timer_settime(timer
, 0, &ts
, NULL
) == -1)
130 panic("PosixKvmTimer: Failed to disarm timer\n");
134 PosixKvmTimer::calcResolution()
138 if (clock_getres(clockID
, &ts
) == -1)
139 panic("PosixKvmTimer: Failed to get timer resolution\n");
141 const uint64_t res_ns(ts
.tv_sec
* 1000000000ULL + ts
.tv_nsec
);
142 // We preferrably want ticksFromHostNs() to calculate the the
143 // ceiling rather than truncating the value. However, there are
144 // other cases where truncating is fine, so we just add 1 here to
145 // make sure that the actual resolution is strictly less than what
146 // we return. We could get all kinds of nasty behavior if
147 // arm(resolution) is called and the resulting time is 0 (which
148 // could happen if we truncate the results and the resolution is
150 const Tick
resolution(ticksFromHostNs(res_ns
) + 1);
151 // It might not make sense to enter into KVM for less than a
152 // certain number of host cycles. In some systems (e.g., Linux)
153 // the resolution of the timer we use is 1ns (a few cycles on most
154 // CPUs), which isn't very useful.
155 const Tick
min_cycles(ticksFromHostCycles(MIN_HOST_CYCLES
));
157 return std::max(resolution
, min_cycles
);
161 PerfKvmTimer::PerfKvmTimer(PerfKvmCounter
&ctr
,
162 int signo
, float hostFactor
, Tick hostFreq
)
163 : BaseKvmTimer(signo
, hostFactor
, hostFreq
),
166 hwOverflow
.enableSignals(signo
);
169 PerfKvmTimer::~PerfKvmTimer()
174 PerfKvmTimer::arm(Tick ticks
)
176 hwOverflow
.period(hostCycles(ticks
));
177 hwOverflow
.refresh(1);
181 PerfKvmTimer::disarm()
187 PerfKvmTimer::calcResolution()
189 return ticksFromHostCycles(MIN_HOST_CYCLES
);