'\" t
.\"     Title: libtracefs
.\"    Author: [see the "AUTHOR" section]
.\" Generator: DocBook XSL Stylesheets vsnapshot <http://docbook.sf.net/>
.\"      Date: 10/08/2022
.\"    Manual: libtracefs Manual
.\"    Source: libtracefs 1.5.0
.\"  Language: English
.\"
.TH "LIBTRACEFS" "3" "10/08/2022" "libtracefs 1\&.5\&.0" "libtracefs Manual"
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.SH "NAME"
tracefs_instance_set_affinity, tracefs_instance_set_affinity_set, tracefs_instance_set_affinity_raw, tracefs_instance_get_affinity, tracefs_instance_get_affinity_set, tracefs_instance_get_affinity_raw \- Sets or retrieves the affinity for an instance or top level for what CPUs enable tracing\&.
.SH "SYNOPSIS"
.sp
.nf
\fB#include <tracefs\&.h>\fR

int \fBtracefs_instance_set_affinity\fR(struct tracefs_instance *\fIinstance\fR, const char *\fIcpu_str\fR);
int \fBtracefs_instance_set_affinity_set\fR(struct tracefs_instance *\fIinstance\fR, cpu_set_t *\fIset\fR, size_t \fIset_size\fR);
int \fBtracefs_instance_set_affinity_raw\fR(struct tracefs_instance *\fIinstance\fR, const char *\fImask\fR);

char *\fBtracefs_instance_get_affinity\fR(struct tracefs_instance *\fIinstance\fR);
int \fBtracefs_instance_get_affinity_set\fR(struct tracefs_instance *\fIinstance\fR, cpu_set_t *\fIset\fR, size_t \fIset_size\fR);
char *\fBtracefs_instance_get_affinity_raw\fR(struct tracefs_instance *\fIinstance\fR);
.fi
.SH "DESCRIPTION"
.sp
These functions set or retrieve the CPU affinity that limits what CPUs will have tracing enabled for a given instance defined by the \fIinstance\fR parameter\&. If \fIinstance\fR is NULL, then the top level instance is affected\&.
.sp
The \fBtracefs_instance_set_affinity()\fR function takes a string \fIcpu_str\fR that is a list of CPUs to set the affinity for\&. If \fIcpu_str\fR is NULL, then all the CPUs in the system will be set\&. The format of \fIcpu_str\fR is a comma delimited string of decimal numbers with no spaces\&. A range may be specified by a hyphen\&.
.sp
For example: "1,4,6\-8"
.sp
The numbers do not need to be in order except for ranges, where the second number must be equal to or greater than the first\&.
.sp
The \fBtracefs_instance_set_affinity_set()\fR function takes a CPU set defined by \fBCPU_SET\fR(3)\&. The size of the set defined by \fIset_size\fR is the size in bytes of \fIset\fR\&. If \fIset\fR is NULL then all the CPUs on the system will be set, and \fIset_size\fR is ignored\&.
.sp
The \fBtracefs_instance_set_affinity_raw()\fR function takes a string that holds a hexidecimal bitmask, where each 32 bits is separated by a comma\&. For a machine with more that 32 CPUs, to set CPUS 1\-10 and CPU 40:
.sp
.if n \{\
.RS 4
.\}
.nf
"100,000007fe"
.fi
.if n \{\
.RE
.\}
.sp
Where the above is a hex representation of bits 1\-10 and bit 40 being set\&.
.sp
The \fBtracefs_instance_get_affinity()\fR will retrieve the affinity in a human readable form\&.
.sp
For example: "1,4,6\-8"
.sp
The string returned must be freed with \fBfree\fR(3)\&.
.sp
The \fBtracefs_instance_get_affinity_set()\fR will set all the bits in the passed in cpu set (from \fBCPU_SET\fR(3))\&. Note it will not clear any bits that are already set in the set but the CPUs are not\&. If only the bits for the CPUs that are enabled should be set, a CPU_ZERO_S() should be performed on the set before calling this function\&.
.sp
The \fBtracefs_instance_get_affinity_raw()\fR will simply read the instance tracing_cpumask and return that string\&. The returned string must be freed with \fBfree\fR(3)\&.
.SH "RETURN VALUE"
.sp
All the set functions return 0 on success and \-1 on error\&.
.sp
The functions \fBtracefs_instance_get_affinity()\fR and \fBtracefs_instance_get_affinity_raw()\fR returns an allocated string that must be freed with \fBfree\fR(3), or NULL on error\&.
.sp
The function \fBtracefs_instance_get_affinity_set()\fR returns the number of CPUs that were found set, or \-1 on error\&.
.SH "ERRORS"
.sp
The following errors are for all the above calls:
.sp
\fBEFBIG\fR if a CPU is set that is greater than what is in the system\&.
.sp
\fBEINVAL\fR One of the parameters was invalid\&.
.sp
The following errors are for \fBtracefs_instance_set_affinity\fR() and \fBtracefs_instance_set_affinity_set\fR():
.sp
\fBENOMEM\fR Memory allocation error\&.
.sp
\fBENODEV\fR dynamic events of requested type are not configured for the running kernel\&.
.sp
The following errors are just for \fBtracefs_instance_set_affinity\fR()
.sp
\fBEACCES\fR The \fIcpu_str\fR was modified by another thread when processing it\&.
.SH "EXAMPLE"
.sp
.if n \{\
.RS 4
.\}
.nf
#include <sched\&.h>
#include <stdio\&.h>
#include <stdlib\&.h>
#include <tracefs\&.h>

int main (int argc, char **argv)
{
        struct trace_seq seq;
        cpu_set_t *set;
        size_t set_size;
        char *c;
        int cpu1;
        int cpu2;
        int i;

        c = tracefs_instance_get_affinity(NULL);
        printf("The affinity was %s\en", c);
        free(c);

        if (argc < 2) {
                tracefs_instance_set_affinity(NULL, NULL);
                exit(0);
        }
        /* Show example using a set */
        if (argc == 2 && !strchr(argv[1],\*(Aq,\*(Aq)) {
                cpu1 = atoi(argv[1]);
                c = strchr(argv[1], \*(Aq\-\*(Aq);
                if (c++)
                        cpu2 = atoi(c);
                else
                        cpu2 = cpu1;
                if (cpu2 < cpu1) {
                        fprintf(stderr, "Invalid CPU range\en");
                        exit(\-1);
                }
                set = CPU_ALLOC(cpu2 + 1);
                set_size = CPU_ALLOC_SIZE(cpu2 + 1);
                CPU_ZERO_S(set_size, set);
                for ( ; cpu1 <= cpu2; cpu1++)
                        CPU_SET(cpu1, set);
                tracefs_instance_set_affinity_set(NULL, set, set_size);
                CPU_FREE(set);
                exit(0);
        }

        trace_seq_init(&seq);
        for (i = 1; i < argc; i++) {
                if (i > 1)
                        trace_seq_putc(&seq, \*(Aq,\*(Aq);
                trace_seq_puts(&seq, argv[i]);
        }
        trace_seq_terminate(&seq);
        tracefs_instance_set_affinity(NULL, seq\&.buffer);
        trace_seq_destroy(&seq);
        exit(0);

        return 0;
}
.fi
.if n \{\
.RE
.\}
.SH "FILES"
.sp
.if n \{\
.RS 4
.\}
.nf
\fBtracefs\&.h\fR
        Header file to include in order to have access to the library APIs\&.
\fB\-ltracefs\fR
        Linker switch to add when building a program that uses the library\&.
.fi
.if n \{\
.RE
.\}
.SH "SEE ALSO"
.sp
\fBlibtracefs\fR(3), \fBlibtraceevent\fR(3), \fBtrace\-cmd\fR(1)
.SH "AUTHOR"
.sp
.if n \{\
.RS 4
.\}
.nf
\fBSteven Rostedt\fR <\m[blue]\fBrostedt@goodmis\&.org\fR\m[]\&\s-2\u[1]\d\s+2>
\fBTzvetomir Stoyanov\fR <\m[blue]\fBtz\&.stoyanov@gmail\&.com\fR\m[]\&\s-2\u[2]\d\s+2>
.fi
.if n \{\
.RE
.\}
.SH "REPORTING BUGS"
.sp
Report bugs to <\m[blue]\fBlinux\-trace\-devel@vger\&.kernel\&.org\fR\m[]\&\s-2\u[3]\d\s+2>
.SH "LICENSE"
.sp
libtracefs is Free Software licensed under the GNU LGPL 2\&.1
.SH "RESOURCES"
.sp
\m[blue]\fBhttps://git\&.kernel\&.org/pub/scm/libs/libtrace/libtracefs\&.git/\fR\m[]
.SH "COPYING"
.sp
Copyright (C) 2020 VMware, Inc\&. Free use of this software is granted under the terms of the GNU Public License (GPL)\&.
.SH "NOTES"
.IP " 1." 4
rostedt@goodmis.org
.RS 4
\%mailto:rostedt@goodmis.org
.RE
.IP " 2." 4
tz.stoyanov@gmail.com
.RS 4
\%mailto:tz.stoyanov@gmail.com
.RE
.IP " 3." 4
linux-trace-devel@vger.kernel.org
.RS 4
\%mailto:linux-trace-devel@vger.kernel.org
.RE