Revision 483b4ee60edbefdfbff0dd538fb81f368d9e7c0d authored by Suresh Siddha on 04 February 2009, 19:59:44 UTC, committed by Ingo Molnar on 04 February 2009, 21:31:19 UTC
Christian Borntraeger reports: > After a logical cpu offline, even on a complete idle system, there > is one cpu with full ticks. It turns out that nohz.cpu_mask has the > the offlined cpu still set. > > In select_nohz_load_balancer() we check if the system is completely > idle to turn of load balancing. We compare cpu_online_map with > nohz.cpu_mask. Since cpu_online_map is updated on cpu unplug, > but nohz.cpu_mask is not, the check fails and the scheduler believes > that we need an "idle load balancer" even on a fully idle system. > Since the ilb cpu does not deactivate the timer tick this breaks NOHZ. Fix the select_nohz_load_balancer() to not set the nohz.cpu_mask while a cpu is going offline. Reported-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Tested-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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tc-driver.c
/*
* TURBOchannel driver services.
*
* Copyright (c) 2005 James Simmons
* Copyright (c) 2006 Maciej W. Rozycki
*
* Loosely based on drivers/dio/dio-driver.c and
* drivers/pci/pci-driver.c.
*
* This file is subject to the terms and conditions of the GNU
* General Public License. See the file "COPYING" in the main
* directory of this archive for more details.
*/
#include <linux/init.h>
#include <linux/module.h>
#include <linux/tc.h>
/**
* tc_register_driver - register a new TC driver
* @drv: the driver structure to register
*
* Adds the driver structure to the list of registered drivers
* Returns a negative value on error, otherwise 0.
* If no error occurred, the driver remains registered even if
* no device was claimed during registration.
*/
int tc_register_driver(struct tc_driver *tdrv)
{
return driver_register(&tdrv->driver);
}
EXPORT_SYMBOL(tc_register_driver);
/**
* tc_unregister_driver - unregister a TC driver
* @drv: the driver structure to unregister
*
* Deletes the driver structure from the list of registered TC drivers,
* gives it a chance to clean up by calling its remove() function for
* each device it was responsible for, and marks those devices as
* driverless.
*/
void tc_unregister_driver(struct tc_driver *tdrv)
{
driver_unregister(&tdrv->driver);
}
EXPORT_SYMBOL(tc_unregister_driver);
/**
* tc_match_device - tell if a TC device structure has a matching
* TC device ID structure
* @tdrv: the TC driver to earch for matching TC device ID strings
* @tdev: the TC device structure to match against
*
* Used by a driver to check whether a TC device present in the
* system is in its list of supported devices. Returns the matching
* tc_device_id structure or %NULL if there is no match.
*/
const struct tc_device_id *tc_match_device(struct tc_driver *tdrv,
struct tc_dev *tdev)
{
const struct tc_device_id *id = tdrv->id_table;
if (id) {
while (id->name[0] || id->vendor[0]) {
if (strcmp(tdev->name, id->name) == 0 &&
strcmp(tdev->vendor, id->vendor) == 0)
return id;
id++;
}
}
return NULL;
}
EXPORT_SYMBOL(tc_match_device);
/**
* tc_bus_match - Tell if a device structure has a matching
* TC device ID structure
* @dev: the device structure to match against
* @drv: the device driver to search for matching TC device ID strings
*
* Used by a driver to check whether a TC device present in the
* system is in its list of supported devices. Returns 1 if there
* is a match or 0 otherwise.
*/
static int tc_bus_match(struct device *dev, struct device_driver *drv)
{
struct tc_dev *tdev = to_tc_dev(dev);
struct tc_driver *tdrv = to_tc_driver(drv);
const struct tc_device_id *id;
id = tc_match_device(tdrv, tdev);
if (id)
return 1;
return 0;
}
struct bus_type tc_bus_type = {
.name = "tc",
.match = tc_bus_match,
};
EXPORT_SYMBOL(tc_bus_type);
static int __init tc_driver_init(void)
{
return bus_register(&tc_bus_type);
}
postcore_initcall(tc_driver_init);
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