This is a memory monitoring interface implemented with reference to Linux's PSI (Pressure Stall Information),
which can send notifications when the system's remaining memory is below the threshold.
The following example code sets two different thresholds.
When the system memory is below 10MB, a notification is triggered.
When the system memory is below 20 MB, a notification (POLLPRI event) is triggered every 1s.
```
int main(int argc, FAR char *argv[])
{
struct pollfd fds[2];
int ret;
if (argc == 2)
{
char *ptr = malloc(1024*1024*atoi(argv[1]));
printf("Allocating %d MB\n", atoi(argv[1]));
ptr[0] = 0;
return 0;
}
fds[0].fd = open("/proc/pressure/memory", O_RDWR);
fds[1].fd = open("/proc/pressure/memory", O_RDWR);
fds[0].events = POLLPRI;
fds[1].events = POLLPRI;
dprintf(fds[0].fd, "%llu -1", 1024LLU*1024 * 10);
dprintf(fds[1].fd, "%llu 1000000", 1024LLU*1024 * 20);
while (1)
{
ret = poll(fds, 2, -1);
if (ret > 0)
{
printf("Memory pressure: POLLPRI, %d\n", ret);
}
}
return 0;
}
```
https://docs.kernel.org/accounting/psi.html
Signed-off-by: yinshengkai <yinshengkai@xiaomi.com>
VELAPLATFO-12536
This provides the initial hooks for Flattened Device Tree support
with QEMU RV. It also provides a new procfs file that exposes the
fdt to userspace much like the /sys/firmware/fdt endpoint in Linux.
See https://www.kernel.org/doc/Documentation/ABI/testing/sysfs-firmware-ofw
Nodes in the fdt are not yet usable by the OS.
Signed-off-by: Brennan Ashton <bashton@brennanashton.com>
Signed-off-by: liaoao <liaoao@xiaomi.com>
Iobinstrumentation
* mm/iob: Introduces producer/consumer id to every iob call. This is so that the calls can be instrumented to monitor the IOB resources.
* iob instrumentation - Merges producer/consumer enumeration for simpler IOB user.
* fs/procfs: Starts adding support for /proc/iobinfo
* fs/procfs: Finishes first pass of simple IOB user stastics and /proc/iobinfo entry
Approved-by: Gregory Nutt <gnutt@nuttx.org>
