The maximum kilobytes of locked memory that an unprivileged user can
reserve is of 512 kB = 128 pages by default, scaled to the number of
onlined CPUs, which fits well with the tools that use 128 data pages
by default.
However tools actually use 129 pages, because they need one more for
the user control page. Thus the default mlock threshold is not
sufficient for the default tools needs and we always end up to
evaluate the constant mlock rlimit policy, which doesn't have this
scaling with the number of online CPUs.
Hence, on systems that have more than 16 CPUs, we overlap the rlimit
threshold and fail to mmap:
$ perf record ls
Error: failed to mmap with 1 (Operation not permitted)
Just increase the max unprivileged mlock threshold by one page so
that it supports well perf tools even after 16 CPUs.
Reported-by: Han Pingtian <[email protected]>
Reported-by: Peter Zijlstra <[email protected]>
Reported-by: Arnaldo Carvalho de Melo <[email protected]>
Signed-off-by: Frederic Weisbecker <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Stephane Eranian <[email protected]>
Cc: Stable <[email protected]>
---
kernel/perf_event.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 3472bb1..d5943b0 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -145,7 +145,8 @@ static struct srcu_struct pmus_srcu;
*/
int sysctl_perf_event_paranoid __read_mostly = 1;
-int sysctl_perf_event_mlock __read_mostly = 512; /* 'free' kb per user */
+/* Minimum for 128 pages + 1 for the user control page */
+int sysctl_perf_event_mlock __read_mostly = 516; /* 'free' kb per user */
/*
* max perf event sample rate
--
1.7.3.2
Em Wed, Mar 23, 2011 at 07:29:39PM +0100, Frederic Weisbecker escreveu:
> The maximum kilobytes of locked memory that an unprivileged user can
> reserve is of 512 kB = 128 pages by default, scaled to the number of
> onlined CPUs, which fits well with the tools that use 128 data pages
> by default.
>
> However tools actually use 129 pages, because they need one more for
> the user control page. Thus the default mlock threshold is not
> sufficient for the default tools needs and we always end up to
> evaluate the constant mlock rlimit policy, which doesn't have this
> scaling with the number of online CPUs.
>
> Hence, on systems that have more than 16 CPUs, we overlap the rlimit
> threshold and fail to mmap:
>
> $ perf record ls
> Error: failed to mmap with 1 (Operation not permitted)
>
> Just increase the max unprivileged mlock threshold by one page so
> that it supports well perf tools even after 16 CPUs.
Thanks!
Acked-by: Arnaldo Carvalho de Melo <[email protected]>
> Reported-by: Han Pingtian <[email protected]>
> Reported-by: Peter Zijlstra <[email protected]>
> Reported-by: Arnaldo Carvalho de Melo <[email protected]>
> Signed-off-by: Frederic Weisbecker <[email protected]>
> Cc: Ingo Molnar <[email protected]>
> Cc: Stephane Eranian <[email protected]>
> Cc: Stable <[email protected]>
> ---
> kernel/perf_event.c | 3 ++-
> 1 files changed, 2 insertions(+), 1 deletions(-)
>
> diff --git a/kernel/perf_event.c b/kernel/perf_event.c
> index 3472bb1..d5943b0 100644
> --- a/kernel/perf_event.c
> +++ b/kernel/perf_event.c
> @@ -145,7 +145,8 @@ static struct srcu_struct pmus_srcu;
> */
> int sysctl_perf_event_paranoid __read_mostly = 1;
>
> -int sysctl_perf_event_mlock __read_mostly = 512; /* 'free' kb per user */
> +/* Minimum for 128 pages + 1 for the user control page */
> +int sysctl_perf_event_mlock __read_mostly = 516; /* 'free' kb per user */
>
> /*
> * max perf event sample rate
> --
> 1.7.3.2
Commit-ID: 880f57318450dbead6a03f9e31a1468924d6dd88
Gitweb: http://git.kernel.org/tip/880f57318450dbead6a03f9e31a1468924d6dd88
Author: Frederic Weisbecker <[email protected]>
AuthorDate: Wed, 23 Mar 2011 19:29:39 +0100
Committer: Ingo Molnar <[email protected]>
CommitDate: Wed, 23 Mar 2011 20:57:04 +0100
perf: Better fit max unprivileged mlock pages for tools needs
The maximum kilobytes of locked memory that an unprivileged user
can reserve is of 512 kB = 128 pages by default, scaled to the
number of onlined CPUs, which fits well with the tools that use
128 data pages by default.
However tools actually use 129 pages, because they need one more
for the user control page. Thus the default mlock threshold is
not sufficient for the default tools needs and we always end up
to evaluate the constant mlock rlimit policy, which doesn't have
this scaling with the number of online CPUs.
Hence, on systems that have more than 16 CPUs, we overlap the
rlimit threshold and fail to mmap:
$ perf record ls
Error: failed to mmap with 1 (Operation not permitted)
Just increase the max unprivileged mlock threshold by one page
so that it supports well perf tools even after 16 CPUs.
Reported-by: Han Pingtian <[email protected]>
Reported-by: Peter Zijlstra <[email protected]>
Reported-by: Arnaldo Carvalho de Melo <[email protected]>
Signed-off-by: Frederic Weisbecker <[email protected]>
Acked-by: Arnaldo Carvalho de Melo <[email protected]>
Cc: Stephane Eranian <[email protected]>
Cc: Stable <[email protected]>
LKML-Reference: <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
---
kernel/perf_event.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 0c71422..c75925c 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -145,7 +145,8 @@ static struct srcu_struct pmus_srcu;
*/
int sysctl_perf_event_paranoid __read_mostly = 1;
-int sysctl_perf_event_mlock __read_mostly = 512; /* 'free' kb per user */
+/* Minimum for 128 pages + 1 for the user control page */
+int sysctl_perf_event_mlock __read_mostly = 516; /* 'free' kb per user */
/*
* max perf event sample rate
On Wed, 2011-03-23 at 19:29 +0100, Frederic Weisbecker wrote:
> -int sysctl_perf_event_mlock __read_mostly = 512; /* 'free' kb per user */
> +/* Minimum for 128 pages + 1 for the user control page */
> +int sysctl_perf_event_mlock __read_mostly = 516; /* 'free' kb per user */
This assumes PAGE_SIZE = 4k..
2011/3/25 Peter Zijlstra <[email protected]>:
> On Wed, 2011-03-23 at 19:29 +0100, Frederic Weisbecker wrote:
>
>> -int sysctl_perf_event_mlock __read_mostly = 512; /* 'free' kb per user */
>> +/* Minimum for 128 pages + 1 for the user control page */
>> +int sysctl_perf_event_mlock __read_mostly = 516; /* 'free' kb per user */
>
> This assumes PAGE_SIZE = 4k..
Yeah, should I rebase the value on top of PAGE_SIZE?
On Fri, 2011-03-25 at 15:50 +0100, Frederic Weisbecker wrote:
> 2011/3/25 Peter Zijlstra <[email protected]>:
> > On Wed, 2011-03-23 at 19:29 +0100, Frederic Weisbecker wrote:
> >
> >> -int sysctl_perf_event_mlock __read_mostly = 512; /* 'free' kb per user */
> >> +/* Minimum for 128 pages + 1 for the user control page */
> >> +int sysctl_perf_event_mlock __read_mostly = 516; /* 'free' kb per user */
> >
> > This assumes PAGE_SIZE = 4k..
>
> Yeah, should I rebase the value on top of PAGE_SIZE?
Possibly yeah, I guess that when the base page size if 64k you really
can't do anything about wasting the whole first page, comes with the
territory.
So that we ensure we allow 129 pages, even if the page size is
different than 4096.
Reported-by: Peter Zijlstra <[email protected]>
Signed-off-by: Frederic Weisbecker <[email protected]>
Cc: Stable <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Stephane Eranian <[email protected]>
---
kernel/perf_event.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index c75925c..fce1b8a 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -146,7 +146,7 @@ static struct srcu_struct pmus_srcu;
int sysctl_perf_event_paranoid __read_mostly = 1;
/* Minimum for 128 pages + 1 for the user control page */
-int sysctl_perf_event_mlock __read_mostly = 516; /* 'free' kb per user */
+int sysctl_perf_event_mlock __read_mostly = (129 * PAGE_SIZE) / 1024; /* 'free' kb per user */
/*
* max perf event sample rate
--
1.7.3.2
On Wed, 2011-03-30 at 16:04 +0200, Frederic Weisbecker wrote:
> +int sysctl_perf_event_mlock __read_mostly = (129 * PAGE_SIZE) / 1024; /* 'free' kb per user */
I'm fairly sure you don't want to do this either:
512 + (PAGE_SIZE / 1024)
should do I think, there's no reason to further inflate things for large
page platforms.
On Wed, Mar 30, 2011 at 04:40:28PM +0200, Peter Zijlstra wrote:
> On Wed, 2011-03-30 at 16:04 +0200, Frederic Weisbecker wrote:
> > +int sysctl_perf_event_mlock __read_mostly = (129 * PAGE_SIZE) / 1024; /* 'free' kb per user */
>
> I'm fairly sure you don't want to do this either:
> 512 + (PAGE_SIZE / 1024)
> should do I think, there's no reason to further inflate things for large
> page platforms.
Right, that also requires to fix tools that use a default number of pages instead
of computing nr_pages on top of page size and a default kb size.
Will respin by fixing both sides.
Thanks.
Ensure we allow 512 kiB + 1 page for user control without
assuming a 4096 page size.
Reported-by: Peter Zijlstra <[email protected]>
Signed-off-by: Frederic Weisbecker <[email protected]>
Cc: Stable <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Stephane Eranian <[email protected]>
---
kernel/perf_event.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index c75925c..2616909 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -145,8 +145,8 @@ static struct srcu_struct pmus_srcu;
*/
int sysctl_perf_event_paranoid __read_mostly = 1;
-/* Minimum for 128 pages + 1 for the user control page */
-int sysctl_perf_event_mlock __read_mostly = 516; /* 'free' kb per user */
+/* Minimum for 512 kiB + 1 user control page */
+int sysctl_perf_event_mlock __read_mostly = 512 + (PAGE_SIZE / 1024); /* 'free' kiB per user */
/*
* max perf event sample rate
--
1.7.3.2
The default setting of perf record is to mmap 128 pages if the user
did not override with -m.
However the page size may vary accross different architecture
settings, giving different default size between each.
Moreover the kernel side still has a default max number of mlocked
pages of 512 kiB + 1 page for unprivileged users. 128 + 1 pages
with page size > 4096 overlaps this threshold.
Thus, better adapt to this limitation and set the default number of
pages to fit those 512 kiB + 1 page.
Signed-off-by: Frederic Weisbecker <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Stephane Eranian <[email protected]>
---
tools/perf/builtin-record.c | 6 +++++-
1 files changed, 5 insertions(+), 1 deletions(-)
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 6febcc1..a7e14bd 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -41,7 +41,7 @@ static u64 user_interval = ULLONG_MAX;
static u64 default_interval = 0;
static unsigned int page_size;
-static unsigned int mmap_pages = 128;
+static unsigned int mmap_pages = UINT_MAX;
static unsigned int user_freq = UINT_MAX;
static int freq = 1000;
static int output;
@@ -506,6 +506,10 @@ static int __cmd_record(int argc, const char **argv)
if (have_tracepoints(&evsel_list->entries))
perf_header__set_feat(&session->header, HEADER_TRACE_INFO);
+ /* 512 kiB: default amount of unprivileged mlocked memory */
+ if (mmap_pages == UINT_MAX)
+ mmap_pages = (512 * 1024) / page_size;
+
if (forks) {
child_pid = fork();
if (child_pid < 0) {
--
1.7.3.2
On Thu, 2011-03-31 at 03:35 +0200, Frederic Weisbecker wrote:
> The default setting of perf record is to mmap 128 pages if the user
> did not override with -m.
> However the page size may vary accross different architecture
> settings, giving different default size between each.
>
> Moreover the kernel side still has a default max number of mlocked
> pages of 512 kiB + 1 page for unprivileged users. 128 + 1 pages
> with page size > 4096 overlaps this threshold.
>
> Thus, better adapt to this limitation and set the default number of
> pages to fit those 512 kiB + 1 page.
>
> Signed-off-by: Frederic Weisbecker <[email protected]>
> Cc: Ingo Molnar <[email protected]>
> Cc: Peter Zijlstra <[email protected]>
> Cc: Arnaldo Carvalho de Melo <[email protected]>
> Cc: Paul Mackerras <[email protected]>
> Cc: Stephane Eranian <[email protected]>
> ---
> tools/perf/builtin-record.c | 6 +++++-
> 1 files changed, 5 insertions(+), 1 deletions(-)
>
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index 6febcc1..a7e14bd 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -41,7 +41,7 @@ static u64 user_interval = ULLONG_MAX;
> static u64 default_interval = 0;
>
> static unsigned int page_size;
> -static unsigned int mmap_pages = 128;
> +static unsigned int mmap_pages = UINT_MAX;
> static unsigned int user_freq = UINT_MAX;
> static int freq = 1000;
> static int output;
> @@ -506,6 +506,10 @@ static int __cmd_record(int argc, const char **argv)
> if (have_tracepoints(&evsel_list->entries))
> perf_header__set_feat(&session->header, HEADER_TRACE_INFO);
>
> + /* 512 kiB: default amount of unprivileged mlocked memory */
> + if (mmap_pages == UINT_MAX)
> + mmap_pages = (512 * 1024) / page_size;
> +
> if (forks) {
> child_pid = fork();
> if (child_pid < 0) {
Ok, these two patches look good, I'll queue them. However a follow up
might be to change the perf-record parameter from nr_pages to kb, which
is a much more user friendly interface anyway ;-)
On Thu, Mar 31, 2011 at 10:09:52AM +0200, Peter Zijlstra wrote:
> On Thu, 2011-03-31 at 03:35 +0200, Frederic Weisbecker wrote:
> > The default setting of perf record is to mmap 128 pages if the user
> > did not override with -m.
> > However the page size may vary accross different architecture
> > settings, giving different default size between each.
> >
> > Moreover the kernel side still has a default max number of mlocked
> > pages of 512 kiB + 1 page for unprivileged users. 128 + 1 pages
> > with page size > 4096 overlaps this threshold.
> >
> > Thus, better adapt to this limitation and set the default number of
> > pages to fit those 512 kiB + 1 page.
> >
> > Signed-off-by: Frederic Weisbecker <[email protected]>
> > Cc: Ingo Molnar <[email protected]>
> > Cc: Peter Zijlstra <[email protected]>
> > Cc: Arnaldo Carvalho de Melo <[email protected]>
> > Cc: Paul Mackerras <[email protected]>
> > Cc: Stephane Eranian <[email protected]>
> > ---
> > tools/perf/builtin-record.c | 6 +++++-
> > 1 files changed, 5 insertions(+), 1 deletions(-)
> >
> > diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> > index 6febcc1..a7e14bd 100644
> > --- a/tools/perf/builtin-record.c
> > +++ b/tools/perf/builtin-record.c
> > @@ -41,7 +41,7 @@ static u64 user_interval = ULLONG_MAX;
> > static u64 default_interval = 0;
> >
> > static unsigned int page_size;
> > -static unsigned int mmap_pages = 128;
> > +static unsigned int mmap_pages = UINT_MAX;
> > static unsigned int user_freq = UINT_MAX;
> > static int freq = 1000;
> > static int output;
> > @@ -506,6 +506,10 @@ static int __cmd_record(int argc, const char **argv)
> > if (have_tracepoints(&evsel_list->entries))
> > perf_header__set_feat(&session->header, HEADER_TRACE_INFO);
> >
> > + /* 512 kiB: default amount of unprivileged mlocked memory */
> > + if (mmap_pages == UINT_MAX)
> > + mmap_pages = (512 * 1024) / page_size;
> > +
> > if (forks) {
> > child_pid = fork();
> > if (child_pid < 0) {
>
> Ok, these two patches look good, I'll queue them. However a follow up
> might be to change the perf-record parameter from nr_pages to kb, which
> is a much more user friendly interface anyway ;-)
Agreed. I just wanted to keep that -m around on top of nr_pages beacuse
we have some tools/scripts relying on it, like perf lock, which need to
be changed as well.
We need a new option for this I think, and deprecate -m later perhaps, the
time for external users to migrate? Or just remove -m but it's certainly
going to be replaced soon.
Commit-ID: 20443384fe090c5f8aeb016e7e85659c5bbdd69f
Gitweb: http://git.kernel.org/tip/20443384fe090c5f8aeb016e7e85659c5bbdd69f
Author: Frederic Weisbecker <[email protected]>
AuthorDate: Thu, 31 Mar 2011 03:33:29 +0200
Committer: Ingo Molnar <[email protected]>
CommitDate: Thu, 31 Mar 2011 13:02:54 +0200
perf: Rebase max unprivileged mlock threshold on top of page size
Ensure we allow 512 kiB + 1 page for user control without
assuming a 4096 bytes page size.
Reported-by: Peter Zijlstra <[email protected]>
Signed-off-by: Frederic Weisbecker <[email protected]>
Signed-off-by: Peter Zijlstra <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Stephane Eranian <[email protected]>
Cc: <[email protected]>
LKML-Reference: <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
---
kernel/perf_event.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index c75925c..2616909 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -145,8 +145,8 @@ static struct srcu_struct pmus_srcu;
*/
int sysctl_perf_event_paranoid __read_mostly = 1;
-/* Minimum for 128 pages + 1 for the user control page */
-int sysctl_perf_event_mlock __read_mostly = 516; /* 'free' kb per user */
+/* Minimum for 512 kiB + 1 user control page */
+int sysctl_perf_event_mlock __read_mostly = 512 + (PAGE_SIZE / 1024); /* 'free' kiB per user */
/*
* max perf event sample rate
Commit-ID: 800cd25c12981c99e5401c3551ffffd99f1c6c85
Gitweb: http://git.kernel.org/tip/800cd25c12981c99e5401c3551ffffd99f1c6c85
Author: Frederic Weisbecker <[email protected]>
AuthorDate: Thu, 31 Mar 2011 03:35:24 +0200
Committer: Ingo Molnar <[email protected]>
CommitDate: Thu, 31 Mar 2011 13:02:55 +0200
perf: mmap 512 kiB by default
The default setting of perf record is to mmap 128 pages if the user
did not override with -m.
However the page size may vary accross different architecture
settings, giving different default size between each.
Moreover the kernel side still has a default max number of mlocked
pages of 512 kiB + 1 page for unprivileged users. 128 + 1 pages
with page size > 4096 overlaps this threshold.
Thus, better adapt to this limitation and set the default number of
pages to fit those 512 kiB + 1 page.
Signed-off-by: Frederic Weisbecker <[email protected]>
Signed-off-by: Peter Zijlstra <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Stephane Eranian <[email protected]>
LKML-Reference: <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
---
tools/perf/builtin-record.c | 6 +++++-
1 files changed, 5 insertions(+), 1 deletions(-)
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index db6adec..17d1dcb 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -41,7 +41,7 @@ static u64 user_interval = ULLONG_MAX;
static u64 default_interval = 0;
static unsigned int page_size;
-static unsigned int mmap_pages = 128;
+static unsigned int mmap_pages = UINT_MAX;
static unsigned int user_freq = UINT_MAX;
static int freq = 1000;
static int output;
@@ -513,6 +513,10 @@ static int __cmd_record(int argc, const char **argv)
if (have_tracepoints(&evsel_list->entries))
perf_header__set_feat(&session->header, HEADER_TRACE_INFO);
+ /* 512 kiB: default amount of unprivileged mlocked memory */
+ if (mmap_pages == UINT_MAX)
+ mmap_pages = (512 * 1024) / page_size;
+
if (forks) {
child_pid = fork();
if (child_pid < 0) {