record/replay fixes, maybe for 8.2 or for post release stable?

[PATCH 08/11] replay: introduce a central report point for sync errors

Posted by Alex Bennée 11 months, 3 weeks ago

Figuring out why replay has failed is tricky at the best of times.
Lets centralise the reporting of a replay sync error and add a little
bit of extra information to help with debugging.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
---
 replay/replay-internal.h | 12 ++++++++++++
 replay/replay-char.c     |  6 ++----
 replay/replay-internal.c |  1 +
 replay/replay.c          |  9 +++++++++
 4 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/replay/replay-internal.h b/replay/replay-internal.h
index 1bc8fd5086..709e2eb4cb 100644
--- a/replay/replay-internal.h
+++ b/replay/replay-internal.h
@@ -74,6 +74,7 @@ enum ReplayEvents {
  * @cached_clock: Cached clocks values
  * @current_icount: number of processed instructions
  * @instruction_count: number of instructions until next event
+ * @current_event: current event index
  * @data_kind: current event
  * @has_unread_data: true if event not yet processed
  * @file_offset: offset into replay log at replay snapshot
@@ -84,6 +85,7 @@ typedef struct ReplayState {
     int64_t cached_clock[REPLAY_CLOCK_COUNT];
     uint64_t current_icount;
     int instruction_count;
+    unsigned int current_event;
     unsigned int data_kind;
     bool has_unread_data;
     uint64_t file_offset;
@@ -188,6 +190,16 @@ void replay_event_net_save(void *opaque);
 /*! Reads network from the file. */
 void *replay_event_net_load(void);
 
+/* Diagnostics */
+
+/**
+ * replay_sync_error(): report sync error and exit
+ *
+ * When we reach an error condition we want to report it centrally so
+ * we can also dump some useful information into the logs.
+ */
+G_NORETURN void replay_sync_error(const char *error);
+
 /* VMState-related functions */
 
 /* Registers replay VMState.
diff --git a/replay/replay-char.c b/replay/replay-char.c
index a31aded032..72b1f832dd 100644
--- a/replay/replay-char.c
+++ b/replay/replay-char.c
@@ -113,8 +113,7 @@ void replay_char_write_event_load(int *res, int *offset)
         *offset = replay_get_dword();
         replay_finish_event();
     } else {
-        error_report("Missing character write event in the replay log");
-        exit(1);
+        replay_sync_error("Missing character write event in the replay log");
     }
 }
 
@@ -135,8 +134,7 @@ int replay_char_read_all_load(uint8_t *buf)
         replay_finish_event();
         return res;
     } else {
-        error_report("Missing character read all event in the replay log");
-        exit(1);
+        replay_sync_error("Missing character read all event in the replay log");
     }
 }
 
diff --git a/replay/replay-internal.c b/replay/replay-internal.c
index 634025096e..654b99cfb5 100644
--- a/replay/replay-internal.c
+++ b/replay/replay-internal.c
@@ -175,6 +175,7 @@ void replay_fetch_data_kind(void)
     if (replay_file) {
         if (!replay_state.has_unread_data) {
             replay_state.data_kind = replay_get_byte();
+            replay_state.current_event++;
             if (replay_state.data_kind == EVENT_INSTRUCTION) {
                 replay_state.instruction_count = replay_get_dword();
             }
diff --git a/replay/replay.c b/replay/replay.c
index d729214197..e83c01285c 100644
--- a/replay/replay.c
+++ b/replay/replay.c
@@ -226,6 +226,14 @@ bool replay_has_event(void)
     return res;
 }
 
+G_NORETURN void replay_sync_error(const char *error)
+{
+    error_report("%s (insn total %"PRId64"/%d left, event %u/%u)", error,
+                 replay_state.current_icount, replay_state.instruction_count,
+                 replay_state.current_event, replay_state.data_kind);
+    abort();
+}
+
 static void replay_enable(const char *fname, int mode)
 {
     const char *fmode = NULL;
@@ -258,6 +266,7 @@ static void replay_enable(const char *fname, int mode)
     replay_state.data_kind = -1;
     replay_state.instruction_count = 0;
     replay_state.current_icount = 0;
+    replay_state.current_event = 0;
     replay_state.has_unread_data = false;
 
     /* skip file header for RECORD and check it for PLAY */
-- 
2.39.2

Re: [PATCH 08/11] replay: introduce a central report point for sync errors

Posted by Richard Henderson 11 months, 3 weeks ago

On 12/5/23 12:41, Alex Bennée wrote:
> Figuring out why replay has failed is tricky at the best of times.
> Lets centralise the reporting of a replay sync error and add a little
> bit of extra information to help with debugging.
> 
> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
> ---
>   replay/replay-internal.h | 12 ++++++++++++
>   replay/replay-char.c     |  6 ++----
>   replay/replay-internal.c |  1 +
>   replay/replay.c          |  9 +++++++++
>   4 files changed, 24 insertions(+), 4 deletions(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>


r~

Re: [PATCH 08/11] replay: introduce a central report point for sync errors

Posted by Philippe Mathieu-Daudé 11 months, 3 weeks ago

Hi Alex,

On 5/12/23 21:41, Alex Bennée wrote:
> Figuring out why replay has failed is tricky at the best of times.
> Lets centralise the reporting of a replay sync error and add a little
> bit of extra information to help with debugging.
> 
> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
> ---
>   replay/replay-internal.h | 12 ++++++++++++
>   replay/replay-char.c     |  6 ++----
>   replay/replay-internal.c |  1 +
>   replay/replay.c          |  9 +++++++++
>   4 files changed, 24 insertions(+), 4 deletions(-)
> 
> diff --git a/replay/replay-internal.h b/replay/replay-internal.h
> index 1bc8fd5086..709e2eb4cb 100644
> --- a/replay/replay-internal.h
> +++ b/replay/replay-internal.h
> @@ -74,6 +74,7 @@ enum ReplayEvents {
>    * @cached_clock: Cached clocks values
>    * @current_icount: number of processed instructions
>    * @instruction_count: number of instructions until next event
> + * @current_event: current event index
>    * @data_kind: current event
>    * @has_unread_data: true if event not yet processed
>    * @file_offset: offset into replay log at replay snapshot
> @@ -84,6 +85,7 @@ typedef struct ReplayState {
>       int64_t cached_clock[REPLAY_CLOCK_COUNT];
>       uint64_t current_icount;
>       int instruction_count;
> +    unsigned int current_event;
>       unsigned int data_kind;
>       bool has_unread_data;
>       uint64_t file_offset;
Shouldn't this field be migrated?

Re: [PATCH 08/11] replay: introduce a central report point for sync errors

Posted by Richard Henderson 11 months, 3 weeks ago

On 12/6/23 03:35, Philippe Mathieu-Daudé wrote:
> Hi Alex,
> 
> On 5/12/23 21:41, Alex Bennée wrote:
>> Figuring out why replay has failed is tricky at the best of times.
>> Lets centralise the reporting of a replay sync error and add a little
>> bit of extra information to help with debugging.
>>
>> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
>> ---
>>   replay/replay-internal.h | 12 ++++++++++++
>>   replay/replay-char.c     |  6 ++----
>>   replay/replay-internal.c |  1 +
>>   replay/replay.c          |  9 +++++++++
>>   4 files changed, 24 insertions(+), 4 deletions(-)
>>
>> diff --git a/replay/replay-internal.h b/replay/replay-internal.h
>> index 1bc8fd5086..709e2eb4cb 100644
>> --- a/replay/replay-internal.h
>> +++ b/replay/replay-internal.h
>> @@ -74,6 +74,7 @@ enum ReplayEvents {
>>    * @cached_clock: Cached clocks values
>>    * @current_icount: number of processed instructions
>>    * @instruction_count: number of instructions until next event
>> + * @current_event: current event index
>>    * @data_kind: current event
>>    * @has_unread_data: true if event not yet processed
>>    * @file_offset: offset into replay log at replay snapshot
>> @@ -84,6 +85,7 @@ typedef struct ReplayState {
>>       int64_t cached_clock[REPLAY_CLOCK_COUNT];
>>       uint64_t current_icount;
>>       int instruction_count;
>> +    unsigned int current_event;
>>       unsigned int data_kind;
>>       bool has_unread_data;
>>       uint64_t file_offset;
> Shouldn't this field be migrated?

No, it's for diagnostic use only.


r~

Re: [PATCH 08/11] replay: introduce a central report point for sync errors

Posted by Pavel Dovgalyuk 11 months, 3 weeks ago

On 06.12.2023 19:48, Richard Henderson wrote:
> On 12/6/23 03:35, Philippe Mathieu-Daudé wrote:
>> Hi Alex,
>>
>> On 5/12/23 21:41, Alex Bennée wrote:
>>> Figuring out why replay has failed is tricky at the best of times.
>>> Lets centralise the reporting of a replay sync error and add a little
>>> bit of extra information to help with debugging.
>>>
>>> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
>>> ---
>>>   replay/replay-internal.h | 12 ++++++++++++
>>>   replay/replay-char.c     |  6 ++----
>>>   replay/replay-internal.c |  1 +
>>>   replay/replay.c          |  9 +++++++++
>>>   4 files changed, 24 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/replay/replay-internal.h b/replay/replay-internal.h
>>> index 1bc8fd5086..709e2eb4cb 100644
>>> --- a/replay/replay-internal.h
>>> +++ b/replay/replay-internal.h
>>> @@ -74,6 +74,7 @@ enum ReplayEvents {
>>>    * @cached_clock: Cached clocks values
>>>    * @current_icount: number of processed instructions
>>>    * @instruction_count: number of instructions until next event
>>> + * @current_event: current event index
>>>    * @data_kind: current event
>>>    * @has_unread_data: true if event not yet processed
>>>    * @file_offset: offset into replay log at replay snapshot
>>> @@ -84,6 +85,7 @@ typedef struct ReplayState {
>>>       int64_t cached_clock[REPLAY_CLOCK_COUNT];
>>>       uint64_t current_icount;
>>>       int instruction_count;
>>> +    unsigned int current_event;
>>>       unsigned int data_kind;
>>>       bool has_unread_data;
>>>       uint64_t file_offset;
>> Shouldn't this field be migrated?
> 
> No, it's for diagnostic use only.

It should be migrated, because RR may be started from the snapshot, 
which references the middle of replayed scenario.


Pavel Dovgalyuk