qemu/translate-common.c
Jan Kiszka 8d04fb55de tcg: drop global lock during TCG code execution
This finally allows TCG to benefit from the iothread introduction: Drop
the global mutex while running pure TCG CPU code. Reacquire the lock
when entering MMIO or PIO emulation, or when leaving the TCG loop.

We have to revert a few optimization for the current TCG threading
model, namely kicking the TCG thread in qemu_mutex_lock_iothread and not
kicking it in qemu_cpu_kick. We also need to disable RAM block
reordering until we have a more efficient locking mechanism at hand.

Still, a Linux x86 UP guest and my Musicpal ARM model boot fine here.
These numbers demonstrate where we gain something:

20338 jan       20   0  331m  75m 6904 R   99  0.9   0:50.95 qemu-system-arm
20337 jan       20   0  331m  75m 6904 S   20  0.9   0:26.50 qemu-system-arm

The guest CPU was fully loaded, but the iothread could still run mostly
independent on a second core. Without the patch we don't get beyond

32206 jan       20   0  330m  73m 7036 R   82  0.9   1:06.00 qemu-system-arm
32204 jan       20   0  330m  73m 7036 S   21  0.9   0:17.03 qemu-system-arm

We don't benefit significantly, though, when the guest is not fully
loading a host CPU.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Message-Id: <1439220437-23957-10-git-send-email-fred.konrad@greensocs.com>
[FK: Rebase, fix qemu_devices_reset deadlock, rm address_space_* mutex]
Signed-off-by: KONRAD Frederic <fred.konrad@greensocs.com>
[EGC: fixed iothread lock for cpu-exec IRQ handling]
Signed-off-by: Emilio G. Cota <cota@braap.org>
[AJB: -smp single-threaded fix, clean commit msg, BQL fixes]
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Reviewed-by: Pranith Kumar <bobby.prani@gmail.com>
[PM: target-arm changes]
Acked-by: Peter Maydell <peter.maydell@linaro.org>
2017-02-24 10:32:45 +00:00

60 lines
1.8 KiB
C

/*
* Host code generation common components
*
* Copyright (c) 2015 Peter Crosthwaite <crosthwaite.peter@gmail.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/
#include "qemu/osdep.h"
#include "qemu-common.h"
#include "qom/cpu.h"
#include "sysemu/cpus.h"
#include "qemu/main-loop.h"
uintptr_t qemu_real_host_page_size;
intptr_t qemu_real_host_page_mask;
#ifndef CONFIG_USER_ONLY
/* mask must never be zero, except for A20 change call */
static void tcg_handle_interrupt(CPUState *cpu, int mask)
{
int old_mask;
g_assert(qemu_mutex_iothread_locked());
old_mask = cpu->interrupt_request;
cpu->interrupt_request |= mask;
/*
* If called from iothread context, wake the target cpu in
* case its halted.
*/
if (!qemu_cpu_is_self(cpu)) {
qemu_cpu_kick(cpu);
} else {
if (use_icount) {
cpu->icount_decr.u16.high = 0xffff;
if (!cpu->can_do_io
&& (mask & ~old_mask) != 0) {
cpu_abort(cpu, "Raised interrupt while not in I/O function");
}
} else {
cpu->tcg_exit_req = 1;
}
}
}
CPUInterruptHandler cpu_interrupt_handler = tcg_handle_interrupt;
#endif