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/*
* Copyright (C) 2006, Intel Corporation
* Copyright (C) 2012, Neil Horman <nhorman@tuxdriver.com>
*
* This file is part of irqbalance
*
* This program file is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; version 2 of the License.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program in a file named COPYING; if not, write to the
* Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301 USA
*/
/*
* This file contains the code to communicate a selected distribution / mapping
* of interrupts to the kernel.
*/
#include "config.h"
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdint.h>
#include <string.h>
#include "irqbalance.h"
static int check_affinity(struct irq_info *info, cpumask_t applied_mask)
{
cpumask_t current_mask;
char buf[PATH_MAX];
sprintf(buf, "/proc/irq/%i/smp_affinity", info->irq);
if (process_one_line(buf, get_mask_from_bitmap, ¤t_mask) < 0)
return 1;
return cpus_equal(applied_mask, current_mask);
}
static void activate_mapping(struct irq_info *info, void *data __attribute__((unused)))
{
char buf[PATH_MAX];
FILE *file;
int errsave, ret;
cpumask_t applied_mask;
/*
* only activate mappings for irqs that have moved
*/
if (!info->moved)
return;
if (!info->assigned_obj)
return;
/* activate only online cpus, otherwise writing to procfs returns EOVERFLOW */
cpus_and(applied_mask, cpu_online_map, info->assigned_obj->mask);
/*
* Don't activate anything for which we have an invalid mask
*/
if (check_affinity(info, applied_mask)) {
info->moved = 0; /* nothing to do, mark as done */
return;
}
sprintf(buf, "/proc/irq/%i/smp_affinity", info->irq);
file = fopen(buf, "w");
errsave = errno;
if (!file)
goto error;
cpumask_scnprintf(buf, PATH_MAX, applied_mask);
ret = fprintf(file, "%s", buf);
errsave = errno;
fflush(file);
if (fclose(file)) {
errsave = errno;
goto error;
}
if (ret < 0)
goto error;
info->moved = 0; /*migration is done*/
return;
error:
log(TO_ALL, LOG_WARNING,
"Cannot change IRQ %i affinity: %s\n",
info->irq, strerror(errsave));
switch (errsave) {
case ENOSPC: /* Specified CPU APIC is full. */
case EAGAIN: /* Interrupted by signal. */
case EBUSY: /* Affinity change already in progress. */
case EINVAL: /* IRQ would be bound to no CPU. */
case ERANGE: /* CPU in mask is offline. */
case ENOMEM: /* Kernel cannot allocate CPU mask. */
/* Do not blacklist the IRQ on transient errors. */
break;
default:
/* Any other error is considered permanent. */
info->level = BALANCE_NONE;
info->moved = 0; /* migration impossible, mark as done */
log(TO_ALL, LOG_WARNING, "IRQ %i affinity is now unmanaged\n",
info->irq);
}
}
void activate_mappings(void)
{
for_each_irq(NULL, activate_mapping, NULL);
}
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