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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utsname.c
/*
* Copyright (C) 2004 IBM Corporation
*
* Author: Serge Hallyn <serue@us.ibm.com>
*
* This program 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.
*/
#include <linux/module.h>
#include <linux/uts.h>
#include <linux/utsname.h>
#include <linux/err.h>
#include <linux/slab.h>
static struct uts_namespace *create_uts_ns(void)
{
struct uts_namespace *uts_ns;
uts_ns = kmalloc(sizeof(struct uts_namespace), GFP_KERNEL);
if (uts_ns)
kref_init(&uts_ns->kref);
return uts_ns;
}
/*
* Clone a new ns copying an original utsname, setting refcount to 1
* @old_ns: namespace to clone
* Return NULL on error (failure to kmalloc), new ns otherwise
*/
static struct uts_namespace *clone_uts_ns(struct uts_namespace *old_ns)
{
struct uts_namespace *ns;
ns = create_uts_ns();
if (!ns)
return ERR_PTR(-ENOMEM);
down_read(&uts_sem);
memcpy(&ns->name, &old_ns->name, sizeof(ns->name));
up_read(&uts_sem);
return ns;
}
/*
* Copy task tsk's utsname namespace, or clone it if flags
* specifies CLONE_NEWUTS. In latter case, changes to the
* utsname of this process won't be seen by parent, and vice
* versa.
*/
struct uts_namespace *copy_utsname(unsigned long flags, struct uts_namespace *old_ns)
{
struct uts_namespace *new_ns;
BUG_ON(!old_ns);
get_uts_ns(old_ns);
if (!(flags & CLONE_NEWUTS))
return old_ns;
new_ns = clone_uts_ns(old_ns);
put_uts_ns(old_ns);
return new_ns;
}
void free_uts_ns(struct kref *kref)
{
struct uts_namespace *ns;
ns = container_of(kref, struct uts_namespace, kref);
kfree(ns);
}
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