commit 304faf96845b06b4889e1c2ce1b49c3ba9b22462
author Derek Bruening <bruening@google.com> Sat Jun 22 00:26:21 2024
committer GitHub <noreply@github.com> Sat Jun 22 00:26:21 2024
tree e33baf32388324dd144b6601b878a02127cea7cd
parent 44d677f8b4ba21c31a0e2cdd8a2243fb881f0cd2

i#6822 unscheduled: Add start-unscheduled support (#6851)

Adds support for threads starting out in an "unscheduled" state. This is
accomplished by always reading ahead in each input and looking for a
TRACE_MARKER_TYPE_SYSCALL_UNSCHEDULE marker *before* the first
instruction. Normally such a marker indicates the invocation of a system
call and is after the system call instruction; for start-unscheduled
threads it is present at the system call exit at the start of the trace.

Changes the scheduler's virtual method process_next_initial_record() to
make the booleans on finding certain markers input-and-output parameters
and moves filetype marker handling and timestamp recording into the
function. This also fixes a problem where an input's initial
next_timestamp was replaced with the 2nd timestamp if a subclass read
ahead.

The extra readahead causes complexities elsewhere which are addressed:
+ The reader caches the last cpuid to use for synthetic recores on
skipping.
+ Generalizes the existing scheduler handling of readahead (the
"recorded_in_schedule" field in input_info_t) to store a count of
pre-read instructions, which will generally be either 0 or 1. Adds a new
internal interface get_instr_ordinal() to get the input reader's
instruction ordinal minus the pre-read count.

Changes raw2trace's virtual function process_marker_additionally() to
process_marker() and moves all marker processing (including timestamps,
which are not markers in the raw format) there, to better support
subclasses inserting start-unscheduled markers and deciding whether to
insert new markers either before or after pre-existing markers.

Adds a scheduler test for the new feature.

Issue: #6822