Manual browser: _lwp_ctl(2)
|_LWP_CTL(2)||System Calls Manual||_LWP_CTL(2)|
NAME_lwp_ctl — prepare per-LWP communication area between kernel and userland
LIBRARYStandard C Library (libc, -lc)
_lwp_ctl(int features, struct lwpctl **address);
DESCRIPTION_lwp_ctl() prepares per-LWP communication area for the calling LWP, and maps it into the calling process' address space. It takes the following arguments.
The bitwise-OR of the following flags.
- Request lc_curcpu.
- Request lc_pctr.
- The address to store a pointer to lwpctl structure for the calling LWP.
The per-LWP communication area is described by an lwpctl structure. It has following members, depending on features.
- int lc_curcpu
- The integral identifier of the CPU on which the LWP is running, or LWPCTL_CPU_NONE when the LWP is not running on any CPU. It's updated by the kernel and should be considered as read-only for userland. It's available only if requested with the LWPCTL_FEATURE_CURCPU flag.
- int lc_pctr
- The integer which is incremented on every context switches to the LWP. It can be used to detect preemption of the LWP. (thus its name "preemption counter".) It's updated by the kernel and should be considered as read-only for userland. It's available only if requested with the LWPCTL_FEATURE_PCTR flag.
RETURN VALUES_lwp_ctl() returns 0 on success. Otherwise, -1 is returned and errno is set to indicate the error.
|April 13, 2012||NetBSD 7.0|