From: Steve MacLean <[email protected]>
While a JIT is jitting code it will eventually need to commit more pages and
change these pages to executable permissions.
Typically the JIT will want these colocated to minimize branch displacements.
The kernel will coalesce these anonymous mapping with identical permissions
before sending an MMAP event for the new pages. This means the mmap event for
the new pages will include the older pages.
These anonymous mmap events will obscure the jitdump injected pseudo events.
This means that the jitdump generated symbols, machine code, debugging info,
and unwind info will no longer be used.
Observations:
When a process emits a jit dump marker and a jitdump file, the perf-xxx.map
file represents inferior information which has been superceded by the
jitdump jit-xxx.dump file.
Further the '//anon*' mmap events are only required for the legacy
perf-xxx.map mapping.
When attaching to an existing process, the synthetic anon map events are
given a time stamp of -1. These should not obscure the jitdump events which
have an actual time.
Summary:
Use thread->priv to store whether a jitdump file has been processed
During "perf inject --jit", discard "//anon*" mmap events for any pid which
has sucessfully processed a jitdump file.
Committer testing:
// jitdump case
perf record <app with jitdump>
perf inject --jit --input perf.data --output perfjit.data
// verify mmap "//anon" events present initially
perf script --input perf.data --show-mmap-events | grep '//anon'
// verify mmap "//anon" events removed
perf script --input perfjit.data --show-mmap-events | grep '//anon'
// no jitdump case
perf record <app without jitdump>
perf inject --jit --input perf.data --output perfjit.data
// verify mmap "//anon" events present initially
perf script --input perf.data --show-mmap-events | grep '//anon'
// verify mmap "//anon" events not removed
perf script --input perfjit.data --show-mmap-events | grep '//anon'
Repro:
This issue was discovered while testing the initial CoreCLR jitdump
implementation. https://github.com/dotnet/coreclr/pull/26897.
Cc: Peter Zijlstra <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Stephane Eranian <[email protected]>
Cc: [email protected]
Signed-off-by: Steve MacLean <[email protected]>
---
tools/perf/builtin-inject.c | 4 ++--
tools/perf/util/jitdump.c | 31 ++++++++++++++++++++++++++++++-
2 files changed, 32 insertions(+), 3 deletions(-)
diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
index 372ecb3..0f38862 100644
--- a/tools/perf/builtin-inject.c
+++ b/tools/perf/builtin-inject.c
@@ -263,7 +263,7 @@ static int perf_event__jit_repipe_mmap(struct perf_tool *tool,
* if jit marker, then inject jit mmaps and generate ELF images
*/
ret = jit_process(inject->session, &inject->output, machine,
- event->mmap.filename, sample->pid, &n);
+ event->mmap.filename, event->mmap.pid, &n);
if (ret < 0)
return ret;
if (ret) {
@@ -301,7 +301,7 @@ static int perf_event__jit_repipe_mmap2(struct perf_tool *tool,
* if jit marker, then inject jit mmaps and generate ELF images
*/
ret = jit_process(inject->session, &inject->output, machine,
- event->mmap2.filename, sample->pid, &n);
+ event->mmap2.filename, event->mmap2.pid, &n);
if (ret < 0)
return ret;
if (ret) {
diff --git a/tools/perf/util/jitdump.c b/tools/perf/util/jitdump.c
index e3ccb0c..d18596e 100644
--- a/tools/perf/util/jitdump.c
+++ b/tools/perf/util/jitdump.c
@@ -26,6 +26,7 @@
#include "jit.h"
#include "jitdump.h"
#include "genelf.h"
+#include "thread.h"
#include <linux/ctype.h>
#include <linux/zalloc.h>
@@ -749,6 +750,28 @@ static int jit_repipe_debug_info(struct jit_buf_desc *jd, union jr_entry *jr)
return 0;
}
+static void jit_add_pid(struct machine *machine, pid_t pid)
+{
+ struct thread *thread = machine__findnew_thread(machine, pid, pid);
+
+ if (!thread) {
+ pr_err("%s: thread %d not found or created\n", __func__, pid);
+ return;
+ }
+
+ thread->priv = (void *)1;
+}
+
+static bool jit_has_pid(struct machine *machine, pid_t pid)
+{
+ struct thread *thread = machine__find_thread(machine, pid, pid);
+
+ if (!thread)
+ return 0;
+
+ return (bool)thread->priv;
+}
+
int
jit_process(struct perf_session *session,
struct perf_data *output,
@@ -764,8 +787,13 @@ static int jit_repipe_debug_info(struct jit_buf_desc *jd, union jr_entry *jr)
/*
* first, detect marker mmap (i.e., the jitdump mmap)
*/
- if (jit_detect(filename, pid))
+ if (jit_detect(filename, pid)) {
+ // Strip //anon* mmaps if we processed a jitdump for this pid
+ if (jit_has_pid(machine, pid) && (strncmp(filename, "//anon", 6) == 0))
+ return 1;
+
return 0;
+ }
memset(&jd, 0, sizeof(jd));
@@ -784,6 +812,7 @@ static int jit_repipe_debug_info(struct jit_buf_desc *jd, union jr_entry *jr)
ret = jit_inject(&jd, filename);
if (!ret) {
+ jit_add_pid(machine, pid);
*nbytes = jd.bytes_written;
ret = 1;
}
--
1.8.3.1
On Thu, Oct 31, 2019 at 01:30:36PM -0700, Steve MacLean wrote:
> From: Steve MacLean <[email protected]>
>
> While a JIT is jitting code it will eventually need to commit more pages and
> change these pages to executable permissions.
>
> Typically the JIT will want these colocated to minimize branch displacements.
>
> The kernel will coalesce these anonymous mapping with identical permissions
> before sending an MMAP event for the new pages. This means the mmap event for
> the new pages will include the older pages.
>
> These anonymous mmap events will obscure the jitdump injected pseudo events.
> This means that the jitdump generated symbols, machine code, debugging info,
> and unwind info will no longer be used.
>
> Observations:
>
> When a process emits a jit dump marker and a jitdump file, the perf-xxx.map
> file represents inferior information which has been superceded by the
> jitdump jit-xxx.dump file.
>
> Further the '//anon*' mmap events are only required for the legacy
> perf-xxx.map mapping.
>
> When attaching to an existing process, the synthetic anon map events are
> given a time stamp of -1. These should not obscure the jitdump events which
> have an actual time.
>
> Summary:
>
> Use thread->priv to store whether a jitdump file has been processed
I'm ok wih the implementation but not sure about the described JIT/mmap logic, Stephane?
jirka
>
> During "perf inject --jit", discard "//anon*" mmap events for any pid which
> has sucessfully processed a jitdump file.
>
> Committer testing:
>
> // jitdump case
> perf record <app with jitdump>
> perf inject --jit --input perf.data --output perfjit.data
>
> // verify mmap "//anon" events present initially
> perf script --input perf.data --show-mmap-events | grep '//anon'
> // verify mmap "//anon" events removed
> perf script --input perfjit.data --show-mmap-events | grep '//anon'
>
> // no jitdump case
> perf record <app without jitdump>
> perf inject --jit --input perf.data --output perfjit.data
>
> // verify mmap "//anon" events present initially
> perf script --input perf.data --show-mmap-events | grep '//anon'
> // verify mmap "//anon" events not removed
> perf script --input perfjit.data --show-mmap-events | grep '//anon'
>
> Repro:
>
> This issue was discovered while testing the initial CoreCLR jitdump
> implementation. https://github.com/dotnet/coreclr/pull/26897.
>
> Cc: Peter Zijlstra <[email protected]>
> Cc: Ingo Molnar <[email protected]>
> Cc: Arnaldo Carvalho de Melo <[email protected]>
> Cc: Mark Rutland <[email protected]>
> Cc: Alexander Shishkin <[email protected]>
> Cc: Jiri Olsa <[email protected]>
> Cc: Namhyung Kim <[email protected]>
> Cc: Stephane Eranian <[email protected]>
> Cc: [email protected]
> Signed-off-by: Steve MacLean <[email protected]>
> ---
> tools/perf/builtin-inject.c | 4 ++--
> tools/perf/util/jitdump.c | 31 ++++++++++++++++++++++++++++++-
> 2 files changed, 32 insertions(+), 3 deletions(-)
>
> diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
> index 372ecb3..0f38862 100644
> --- a/tools/perf/builtin-inject.c
> +++ b/tools/perf/builtin-inject.c
> @@ -263,7 +263,7 @@ static int perf_event__jit_repipe_mmap(struct perf_tool *tool,
> * if jit marker, then inject jit mmaps and generate ELF images
> */
> ret = jit_process(inject->session, &inject->output, machine,
> - event->mmap.filename, sample->pid, &n);
> + event->mmap.filename, event->mmap.pid, &n);
> if (ret < 0)
> return ret;
> if (ret) {
> @@ -301,7 +301,7 @@ static int perf_event__jit_repipe_mmap2(struct perf_tool *tool,
> * if jit marker, then inject jit mmaps and generate ELF images
> */
> ret = jit_process(inject->session, &inject->output, machine,
> - event->mmap2.filename, sample->pid, &n);
> + event->mmap2.filename, event->mmap2.pid, &n);
> if (ret < 0)
> return ret;
> if (ret) {
> diff --git a/tools/perf/util/jitdump.c b/tools/perf/util/jitdump.c
> index e3ccb0c..d18596e 100644
> --- a/tools/perf/util/jitdump.c
> +++ b/tools/perf/util/jitdump.c
> @@ -26,6 +26,7 @@
> #include "jit.h"
> #include "jitdump.h"
> #include "genelf.h"
> +#include "thread.h"
>
> #include <linux/ctype.h>
> #include <linux/zalloc.h>
> @@ -749,6 +750,28 @@ static int jit_repipe_debug_info(struct jit_buf_desc *jd, union jr_entry *jr)
> return 0;
> }
>
> +static void jit_add_pid(struct machine *machine, pid_t pid)
> +{
> + struct thread *thread = machine__findnew_thread(machine, pid, pid);
> +
> + if (!thread) {
> + pr_err("%s: thread %d not found or created\n", __func__, pid);
> + return;
> + }
> +
> + thread->priv = (void *)1;
> +}
> +
> +static bool jit_has_pid(struct machine *machine, pid_t pid)
> +{
> + struct thread *thread = machine__find_thread(machine, pid, pid);
> +
> + if (!thread)
> + return 0;
> +
> + return (bool)thread->priv;
> +}
> +
> int
> jit_process(struct perf_session *session,
> struct perf_data *output,
> @@ -764,8 +787,13 @@ static int jit_repipe_debug_info(struct jit_buf_desc *jd, union jr_entry *jr)
> /*
> * first, detect marker mmap (i.e., the jitdump mmap)
> */
> - if (jit_detect(filename, pid))
> + if (jit_detect(filename, pid)) {
> + // Strip //anon* mmaps if we processed a jitdump for this pid
> + if (jit_has_pid(machine, pid) && (strncmp(filename, "//anon", 6) == 0))
> + return 1;
> +
> return 0;
> + }
>
> memset(&jd, 0, sizeof(jd));
>
> @@ -784,6 +812,7 @@ static int jit_repipe_debug_info(struct jit_buf_desc *jd, union jr_entry *jr)
>
> ret = jit_inject(&jd, filename);
> if (!ret) {
> + jit_add_pid(machine, pid);
> *nbytes = jd.bytes_written;
> ret = 1;
> }
> --
> 1.8.3.1
>
> > While a JIT is jitting code it will eventually need to commit more
> > pages and change these pages to executable permissions.
> >
> > Typically the JIT will want these colocated to minimize branch displacements.
> >
> > The kernel will coalesce these anonymous mapping with identical
> > permissions before sending an MMAP event for the new pages. This means
> > the mmap event for the new pages will include the older pages.
> >
> > These anonymous mmap events will obscure the jitdump injected pseudo events.
> > This means that the jitdump generated symbols, machine code, debugging
> > info, and unwind info will no longer be used.
> >
> > Observations:
> >
> > When a process emits a jit dump marker and a jitdump file, the
> > perf-xxx.map file represents inferior information which has been
> > superceded by the jitdump jit-xxx.dump file.
> >
> > Further the '//anon*' mmap events are only required for the legacy
> > perf-xxx.map mapping.
> >
> > When attaching to an existing process, the synthetic anon map events
> > are given a time stamp of -1. These should not obscure the jitdump
> > events which have an actual time.
> >
> > Summary:
> >
> > Use thread->priv to store whether a jitdump file has been processed
>
> I'm ok wih the implementation but not sure about the described JIT/mmap logic, Stephane?
>
> jirka
The kernel only seems to coalesce the anonymous mappings when the allocations grow beyond 64K. It may not affect JITs for smaller sets of JITted code. I would guess a javascript JIT engine might not hit this type of problem often.
@Stephane Eranian could you comment.
@Jiri Olsa I am happy to expand the explanation if it would be helpful.
On Sat, Nov 09, 2019 at 04:49:25PM +0000, Steve MacLean wrote:
> > > While a JIT is jitting code it will eventually need to commit more
> > > pages and change these pages to executable permissions.
> > >
> > > Typically the JIT will want these colocated to minimize branch displacements.
> > >
> > > The kernel will coalesce these anonymous mapping with identical
> > > permissions before sending an MMAP event for the new pages. This means
> > > the mmap event for the new pages will include the older pages.
> > >
> > > These anonymous mmap events will obscure the jitdump injected pseudo events.
> > > This means that the jitdump generated symbols, machine code, debugging
> > > info, and unwind info will no longer be used.
> > >
> > > Observations:
> > >
> > > When a process emits a jit dump marker and a jitdump file, the
> > > perf-xxx.map file represents inferior information which has been
> > > superceded by the jitdump jit-xxx.dump file.
> > >
> > > Further the '//anon*' mmap events are only required for the legacy
> > > perf-xxx.map mapping.
> > >
> > > When attaching to an existing process, the synthetic anon map events
> > > are given a time stamp of -1. These should not obscure the jitdump
> > > events which have an actual time.
> > >
> > > Summary:
> > >
> > > Use thread->priv to store whether a jitdump file has been processed
> >
> > I'm ok wih the implementation but not sure about the described JIT/mmap logic, Stephane?
> >
> > jirka
>
> The kernel only seems to coalesce the anonymous mappings when the allocations grow beyond 64K. It may not affect JITs for smaller sets of JITted code. I would guess a javascript JIT engine might not hit this type of problem often.
>
> @Stephane Eranian could you comment.
>
> @Jiri Olsa I am happy to expand the explanation if it would be helpful.
that'd be great, thanks
jirka
> > > > While a JIT is jitting code it will eventually need to commit more
> > > > pages and change these pages to executable permissions.
> > > >
> > > > Typically the JIT will want these colocated to minimize branch displacements.
> > > >
> > > > The kernel will coalesce these anonymous mapping with identical
> > > > permissions before sending an MMAP event for the new pages. This
> > > > means the mmap event for the new pages will include the older pages.
> > > >
> > > > These anonymous mmap events will obscure the jitdump injected pseudo events.
> > > > This means that the jitdump generated symbols, machine code,
> > > > debugging info, and unwind info will no longer be used.
> > > >
> > > > Observations:
> > > >
> > > > When a process emits a jit dump marker and a jitdump file, the
> > > > perf-xxx.map file represents inferior information which has been
> > > > superceded by the jitdump jit-xxx.dump file.
> > > >
> > > > Further the '//anon*' mmap events are only required for the legacy
> > > > perf-xxx.map mapping.
> > > >
> > > > When attaching to an existing process, the synthetic anon map
> > > > events are given a time stamp of -1. These should not obscure the
> > > > jitdump events which have an actual time.
> > > >
> > > > Summary:
> > > >
> > > > Use thread->priv to store whether a jitdump file has been
> > > > processed
> > >
> > > I'm ok wih the implementation but not sure about the described JIT/mmap logic, Stephane?
> > >
> > > jirka
> >
> > The kernel only seems to coalesce the anonymous mappings when the allocations grow beyond 64K. It may not affect JITs for smaller sets of JITted code. I would guess a javascript JIT engine might not hit this type of problem often.
> >
> > @Stephane Eranian could you comment.
> >
> > @Jiri Olsa I am happy to expand the explanation if it would be helpful.
>
> that'd be great, thanks
>
> jirka
>
Here is an expanded description in markdown syntax. If you need additional or
different details let me know.
## perf-<pid>.map and jit-<pid>.dump designs:
When a JIT generates code to be executed, it must allocate memory and
mark it executable using an mmap call.
### perf-<pid>.map design
The perf-<pid>.map assumes that any sample recorded in an anonymous
memory page is JIT code. It then tries to resolve the symbol name by
looking at the process' perf-<pid>.map.
### jit-<pid>.dump design
The jit-<pid>.dump mechanism takes a different approach. It requires a JIT
to write a `<path>/jit-<pid>.dump` file. This file must also be mmapped
so that perf inject -jit can find the file. The JIT must also add
JIT_CODE_LOAD records for any functions it generates. The records are
timestamped using a clock which can be correlated to the perf record
clock.
After perf record, the `perf inject -jit` pass parses the recording
looking for a `<path>/jit-<pid>.dump` file. When it finds the file, it
parses it and for each JIT_CODE_LOAD record:
* creates an elf file `<path>/jitted-<pid>-<code_index>.so
* injects a new mmap record mapping the new elf file into the process.
### Coexistence design
The kernel and perf support both of these mechanisms. We need to make
sure perf works on an app supporting either or both of these mechanisms.
Both designs rely on mmap records to determine how to resolve an ip
address.
The mmap records of both techniques by definition overlap. When the JIT
compiles a method, it must:
* allocate memory (mmap)
* add execution privilege (mprotect or mmap. either will
generate an mmap event form the kernel to perf)
* compile code into memory
* add a function record to perf-<pid>.map and/or jit-<pid>.dump
Because the jit-<pid>.dump mechanism supports greater capabilities, perf
prefers the symbols from jit-<pid>.dump. It implements this based on
timestamp ordering of events. There is an implicit ASSUMPTION that the
JIT_CODE_LOAD record timestamp will be after the // anon mmap event that
was generated during memory allocation or adding the execution privilege setting.
## Problems with the ASSUMPTION
The ASSUMPTION made in the Coexistence design section above is violated
in the following scenario.
### Scenario
While a JIT is jitting code it will eventually need to commit more
pages and change these pages to executable permissions. Typically the
JIT will want these collocated to minimize branch displacements.
The kernel will coalesce these anonymous mapping with identical
permissions before sending an MMAP event for the new pages. The address
range of the new mmap will not be just the most recently mmap pages.
### Symptoms
The coalesced // anon mmap event will be timestamped after the
JIT_CODE_LOAD records. This means it will be used as the most recent
mapping for that entire address range. For remaining events it will look at the
inferior perf-<pid>.map for symbols.
If both mechanisms are supported, the symbol will appear twice with
different module names. This causes weird behavior in reporting.
If only jit-<pid>.dump is supported, the symbol will no longer be resolved.
## Proposed solution
This patch solves the issue by removing // anon mmap events for any
process which has a valid jit-<pid>.dump file.
It tracks on a per process basis to handle the case where some running
apps support jit-<pid>.dump, but some only support perf-<pid>.map.
It adds new assumptions:
* // anon mmap events are only required for perf-<pid>.map support.
* An app that uses jit-<pid>.dump, no longer needs
perf-<pid>.map support. It assumes that any perf-<pid>.map info is
inferior.
## Alternative Solutions
These were also briefly considered
* Change kernel to not coalesce mmap regions.
* Change kernel reporting of coalesced mmap regions to perf. Only
include newly mapped memory.
* Only strip parts of // anon mmap events overlapping existing
jitted-<pid>-<code_index>.so mmap events.
Anything I can do to help get this reviewed?
On Thu, Oct 31, 2019 at 01:30:36PM -0700, Steve MacLean wrote:
> From: Steve MacLean <[email protected]>
>
> While a JIT is jitting code it will eventually need to commit more pages and
> change these pages to executable permissions.
>
> Typically the JIT will want these colocated to minimize branch displacements.
>
> The kernel will coalesce these anonymous mapping with identical permissions
> before sending an MMAP event for the new pages. This means the mmap event for
> the new pages will include the older pages.
>
> These anonymous mmap events will obscure the jitdump injected pseudo events.
> This means that the jitdump generated symbols, machine code, debugging info,
> and unwind info will no longer be used.
>
> Observations:
>
> When a process emits a jit dump marker and a jitdump file, the perf-xxx.map
> file represents inferior information which has been superceded by the
> jitdump jit-xxx.dump file.
>
> Further the '//anon*' mmap events are only required for the legacy
> perf-xxx.map mapping.
>
> When attaching to an existing process, the synthetic anon map events are
> given a time stamp of -1. These should not obscure the jitdump events which
> have an actual time.
>
> Summary:
>
> Use thread->priv to store whether a jitdump file has been processed
>
> During "perf inject --jit", discard "//anon*" mmap events for any pid which
> has sucessfully processed a jitdump file.
>
> Committer testing:
>
> // jitdump case
> perf record <app with jitdump>
> perf inject --jit --input perf.data --output perfjit.data
>
> // verify mmap "//anon" events present initially
> perf script --input perf.data --show-mmap-events | grep '//anon'
> // verify mmap "//anon" events removed
> perf script --input perfjit.data --show-mmap-events | grep '//anon'
>
> // no jitdump case
> perf record <app without jitdump>
> perf inject --jit --input perf.data --output perfjit.data
>
> // verify mmap "//anon" events present initially
> perf script --input perf.data --show-mmap-events | grep '//anon'
> // verify mmap "//anon" events not removed
> perf script --input perfjit.data --show-mmap-events | grep '//anon'
>
> Repro:
>
> This issue was discovered while testing the initial CoreCLR jitdump
> implementation. https://github.com/dotnet/coreclr/pull/26897.
>
Stephane,
are you ok with this fix?
thanks,
jirka
> Cc: Peter Zijlstra <[email protected]>
> Cc: Ingo Molnar <[email protected]>
> Cc: Arnaldo Carvalho de Melo <[email protected]>
> Cc: Mark Rutland <[email protected]>
> Cc: Alexander Shishkin <[email protected]>
> Cc: Jiri Olsa <[email protected]>
> Cc: Namhyung Kim <[email protected]>
> Cc: Stephane Eranian <[email protected]>
> Cc: [email protected]
> Signed-off-by: Steve MacLean <[email protected]>
> ---
> tools/perf/builtin-inject.c | 4 ++--
> tools/perf/util/jitdump.c | 31 ++++++++++++++++++++++++++++++-
> 2 files changed, 32 insertions(+), 3 deletions(-)
>
> diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
> index 372ecb3..0f38862 100644
> --- a/tools/perf/builtin-inject.c
> +++ b/tools/perf/builtin-inject.c
> @@ -263,7 +263,7 @@ static int perf_event__jit_repipe_mmap(struct perf_tool *tool,
> * if jit marker, then inject jit mmaps and generate ELF images
> */
> ret = jit_process(inject->session, &inject->output, machine,
> - event->mmap.filename, sample->pid, &n);
> + event->mmap.filename, event->mmap.pid, &n);
> if (ret < 0)
> return ret;
> if (ret) {
> @@ -301,7 +301,7 @@ static int perf_event__jit_repipe_mmap2(struct perf_tool *tool,
> * if jit marker, then inject jit mmaps and generate ELF images
> */
> ret = jit_process(inject->session, &inject->output, machine,
> - event->mmap2.filename, sample->pid, &n);
> + event->mmap2.filename, event->mmap2.pid, &n);
> if (ret < 0)
> return ret;
> if (ret) {
> diff --git a/tools/perf/util/jitdump.c b/tools/perf/util/jitdump.c
> index e3ccb0c..d18596e 100644
> --- a/tools/perf/util/jitdump.c
> +++ b/tools/perf/util/jitdump.c
> @@ -26,6 +26,7 @@
> #include "jit.h"
> #include "jitdump.h"
> #include "genelf.h"
> +#include "thread.h"
>
> #include <linux/ctype.h>
> #include <linux/zalloc.h>
> @@ -749,6 +750,28 @@ static int jit_repipe_debug_info(struct jit_buf_desc *jd, union jr_entry *jr)
> return 0;
> }
>
> +static void jit_add_pid(struct machine *machine, pid_t pid)
> +{
> + struct thread *thread = machine__findnew_thread(machine, pid, pid);
> +
> + if (!thread) {
> + pr_err("%s: thread %d not found or created\n", __func__, pid);
> + return;
> + }
> +
> + thread->priv = (void *)1;
> +}
> +
> +static bool jit_has_pid(struct machine *machine, pid_t pid)
> +{
> + struct thread *thread = machine__find_thread(machine, pid, pid);
> +
> + if (!thread)
> + return 0;
> +
> + return (bool)thread->priv;
> +}
> +
> int
> jit_process(struct perf_session *session,
> struct perf_data *output,
> @@ -764,8 +787,13 @@ static int jit_repipe_debug_info(struct jit_buf_desc *jd, union jr_entry *jr)
> /*
> * first, detect marker mmap (i.e., the jitdump mmap)
> */
> - if (jit_detect(filename, pid))
> + if (jit_detect(filename, pid)) {
> + // Strip //anon* mmaps if we processed a jitdump for this pid
> + if (jit_has_pid(machine, pid) && (strncmp(filename, "//anon", 6) == 0))
> + return 1;
> +
> return 0;
> + }
>
> memset(&jd, 0, sizeof(jd));
>
> @@ -784,6 +812,7 @@ static int jit_repipe_debug_info(struct jit_buf_desc *jd, union jr_entry *jr)
>
> ret = jit_inject(&jd, filename);
> if (!ret) {
> + jit_add_pid(machine, pid);
> *nbytes = jd.bytes_written;
> ret = 1;
> }
> --
> 1.8.3.1
>
I'd just like to weight in that this patch fixes the issue Steve
mentioned. I have a local experiment using LLVM's ORC jit with jitdump
support and couldn't get any symbols recognized by perf until applying
this patch.
Thank you,
François
On Sat, Dec 28, 2019 at 01:02:13PM -0500, Francois Saint-Jacques wrote:
> I'd just like to weight in that this patch fixes the issue Steve
> mentioned. I have a local experiment using LLVM's ORC jit with jitdump
> support and couldn't get any symbols recognized by perf until applying
> this patch.
great, please reply to the orginal patch post with tested-by
Arnaldo, could you please check on this one?
there was some discussion about used clockid, but Stephane or
any other jit guys did not raise any particular concern AFAICS,
also it's simple enough to revert in case there's any issue
thanks,
jirka
>
> Thank you,
> Fran?ois
>
> it's simple enough to revert in case there's any issue
>
> thanks,
> jirka
Can we go ahead and merge this?
On Mon, Apr 27, 2020 at 10:03:58PM +0000, Steve MacLean wrote:
> > it's simple enough to revert in case there's any issue
> >
> > thanks,
> > jirka
>
> Can we go ahead and merge this?
>
I saw the explanation you posted:
https://lore.kernel.org/lkml/CY4PR21MB0632B5EE447DA9B931CB114DF7740@CY4PR21MB0632.namprd21.prod.outlook.com/
could you please add it to the patch changelog and repost?
as I said I'm ok with the patch, Stephane?
jirka