Pierrick Bouvier <pierrick.bouvier@xxxxxxxxxx> writes: > On 6/13/24 01:54, Philippe Mathieu-Daudé wrote: >> On 12/6/24 17:35, Alex Bennée wrote: >>> From: Pierrick Bouvier <pierrick.bouvier@xxxxxxxxxx> >>> >>> This plugin uses the new time control interface to make decisions >>> about the state of time during the emulation. The algorithm is >>> currently very simple. The user specifies an ips rate which applies >> ... IPS rate (Instructions Per Second) which ... >> >>> per core. If the core runs ahead of its allocated execution time the >>> plugin sleeps for a bit to let real time catch up. Either way time is >>> updated for the emulation as a function of total executed instructions >>> with some adjustments for cores that idle. >>> >>> Examples >>> -------- >>> >>> Slow down execution of /bin/true: >>> $ num_insn=$(./build/qemu-x86_64 -plugin ./build/tests/plugin/libinsn.so -d plugin /bin/true |& grep total | sed -e 's/.*: //') >>> $ time ./build/qemu-x86_64 -plugin ./build/contrib/plugins/libips.so,ips=$(($num_insn/4)) /bin/true >>> real 4.000s >>> >>> Boot a Linux kernel simulating a 250MHz cpu: >>> $ /build/qemu-system-x86_64 -kernel /boot/vmlinuz-6.1.0-21-amd64 -append "console=ttyS0" -plugin ./build/contrib/plugins/libips.so,ips=$((250*1000*1000)) -smp 1 -m 512 >>> check time until kernel panic on serial0 >>> >>> Tested in system mode by booting a full debian system, and using: >>> $ sysbench cpu run >>> Performance decrease linearly with the given number of ips. >>> >>> Signed-off-by: Pierrick Bouvier <pierrick.bouvier@xxxxxxxxxx> >>> Message-Id: <20240530220610.1245424-7-pierrick.bouvier@xxxxxxxxxx> >>> --- >>> contrib/plugins/ips.c | 164 +++++++++++++++++++++++++++++++++++++++ >>> contrib/plugins/Makefile | 1 + >>> 2 files changed, 165 insertions(+) >>> create mode 100644 contrib/plugins/ips.c >>> >>> diff --git a/contrib/plugins/ips.c b/contrib/plugins/ips.c >>> new file mode 100644 >>> index 0000000000..db77729264 >>> --- /dev/null >>> +++ b/contrib/plugins/ips.c >>> @@ -0,0 +1,164 @@ >>> +/* >>> + * ips rate limiting plugin. >> The plugin names are really to packed to my taste (each time I look >> for >> one I have to open most source files to figure out the correct one); so >> please ease my life by using a more descriptive header at least: >> Instructions Per Second (IPS) rate limiting plugin. >> Thanks. >> > > I agree most of the plugin names are pretty cryptic, and they are > lacking a common "help" system, to describe what they do, and which > options are available for them. It's definitely something we could add > in the future. > > Regarding what you reported, I'm totally ok with the change. > > However, since this is a new series, I'm not if I or Alex should > change it. If it's ok for you to modify this Alex, it could be simpler > than waiting for me to push a new patch with just this. Its my tree so I'll fix it up. I'll ask you if I want a respin ;-) -- Alex Bennée Virtualisation Tech Lead @ Linaro
