On 1 February 2017 at 15:05, Alex Bennée <alex.ben...@linaro.org> wrote: > From: Jan Kiszka <jan.kis...@siemens.com> > > 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.kis...@siemens.com> > Message-Id: <1439220437-23957-10-git-send-email-fred.kon...@greensocs.com> > [FK: Rebase, fix qemu_devices_reset deadlock, rm address_space_* mutex] > Signed-off-by: KONRAD Frederic <fred.kon...@greensocs.com> > [EGC: fixed iothread lock for cpu-exec IRQ handling] > Signed-off-by: Emilio G. Cota <c...@braap.org> > [AJB: -smp single-threaded fix, clean commit msg, BQL fixes] > Signed-off-by: Alex Bennée <alex.ben...@linaro.org> > Reviewed-by: Richard Henderson <r...@twiddle.net> > Reviewed-by: Pranith Kumar <bobby.pr...@gmail.com>
target/arm changes: Acked-by: Peter Maydell <peter.mayd...@linaro.org> -- PMM
