Revision 7f453c24b95a085fc7bd35d53b33abc4dc5a048b authored by Peter Zijlstra on 21 July 2009, 11:19:40 UTC, committed by Peter Zijlstra on 22 July 2009, 16:05:56 UTC
Anton noted that for inherited counters the counter-id as provided by PERF_SAMPLE_ID isn't mappable to the id found through PERF_RECORD_ID because each inherited counter gets its own id. His suggestion was to always return the parent counter id, since that is the primary counter id as exposed. However, these inherited counters have a unique identifier so that events like PERF_EVENT_PERIOD and PERF_EVENT_THROTTLE can be specific about which counter gets modified, which is important when trying to normalize the sample streams. This patch removes PERF_EVENT_PERIOD in favour of PERF_SAMPLE_PERIOD, which is more useful anyway, since changing periods became a lot more common than initially thought -- rendering PERF_EVENT_PERIOD the less useful solution (also, PERF_SAMPLE_PERIOD reports the more accurate value, since it reports the value used to trigger the overflow, whereas PERF_EVENT_PERIOD simply reports the requested period changed, which might only take effect on the next cycle). This still leaves us PERF_EVENT_THROTTLE to consider, but since that _should_ be a rare occurrence, and linking it to a primary id is the most useful bit to diagnose the problem, we introduce a PERF_SAMPLE_STREAM_ID, for those few cases where the full reconstruction is important. [Does change the ABI a little, but I see no other way out] Suggested-by: Anton Blanchard <anton@samba.org> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1248095846.15751.8781.camel@twins>
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ipcns_notifier.c
/*
* linux/ipc/ipcns_notifier.c
* Copyright (C) 2007 BULL SA. Nadia Derbey
*
* Notification mechanism for ipc namespaces:
* The callback routine registered in the memory chain invokes the ipcns
* notifier chain with the IPCNS_MEMCHANGED event.
* Each callback routine registered in the ipcns namespace recomputes msgmni
* for the owning namespace.
*/
#include <linux/msg.h>
#include <linux/rcupdate.h>
#include <linux/notifier.h>
#include <linux/nsproxy.h>
#include <linux/ipc_namespace.h>
#include "util.h"
static BLOCKING_NOTIFIER_HEAD(ipcns_chain);
static int ipcns_callback(struct notifier_block *self,
unsigned long action, void *arg)
{
struct ipc_namespace *ns;
switch (action) {
case IPCNS_MEMCHANGED: /* amount of lowmem has changed */
case IPCNS_CREATED:
case IPCNS_REMOVED:
/*
* It's time to recompute msgmni
*/
ns = container_of(self, struct ipc_namespace, ipcns_nb);
/*
* No need to get a reference on the ns: the 1st job of
* free_ipc_ns() is to unregister the callback routine.
* blocking_notifier_chain_unregister takes the wr lock to do
* it.
* When this callback routine is called the rd lock is held by
* blocking_notifier_call_chain.
* So the ipc ns cannot be freed while we are here.
*/
recompute_msgmni(ns);
break;
default:
break;
}
return NOTIFY_OK;
}
int register_ipcns_notifier(struct ipc_namespace *ns)
{
int rc;
memset(&ns->ipcns_nb, 0, sizeof(ns->ipcns_nb));
ns->ipcns_nb.notifier_call = ipcns_callback;
ns->ipcns_nb.priority = IPCNS_CALLBACK_PRI;
rc = blocking_notifier_chain_register(&ipcns_chain, &ns->ipcns_nb);
if (!rc)
ns->auto_msgmni = 1;
return rc;
}
int cond_register_ipcns_notifier(struct ipc_namespace *ns)
{
int rc;
memset(&ns->ipcns_nb, 0, sizeof(ns->ipcns_nb));
ns->ipcns_nb.notifier_call = ipcns_callback;
ns->ipcns_nb.priority = IPCNS_CALLBACK_PRI;
rc = blocking_notifier_chain_cond_register(&ipcns_chain,
&ns->ipcns_nb);
if (!rc)
ns->auto_msgmni = 1;
return rc;
}
void unregister_ipcns_notifier(struct ipc_namespace *ns)
{
blocking_notifier_chain_unregister(&ipcns_chain, &ns->ipcns_nb);
ns->auto_msgmni = 0;
}
int ipcns_notify(unsigned long val)
{
return blocking_notifier_call_chain(&ipcns_chain, val, NULL);
}
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