i#6959: Add exit_if_fraction_left option #7018
Merged
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Adds a new scheduler feature and CLI option exit_if_fraction_left.
This applies to -core_sharded and -core_serial modes. When an input
reaches EOF, if the number of non-EOF inputs left as a fraction of the
original inputs is equal to or less than this value then the scheduler
exits (sets all outputs to EOF) rather than finishing off the final
inputs. This helps avoid long sequences of idles during staggered
endings with fewer inputs left than cores and only a small fraction of
the total instructions left in those inputs.
The default value in scheduler_options_t is 0 as simulators are
typically already choosing to stop at some even point. For analyzers,
however, via the command-line option, the default is 0.05 (i.e., 5%),
which when tested on an large internal trace helps eliminate much of
the final idle time from the cores (just about any value over 0.05
works well: it is not overly sensitive).
Compare the numbers below for today's default with a long idle time
and so distinct differences between the "cpu busy by time" and "cpu
busy by time, ignoring idle past last instr" stats on a 39-core
schedule-stats run of a moderately large trace, with key stats and the
1st 2 cores (for brevity) shown here:
1567052521 instructions
878027975 idles
64.09% cpu busy by record count
82.38% cpu busy by time
96.81% cpu busy by time, ignoring idle past last instr
Core #0 schedule: CccccccOXHhUuuuuAaSEOGOWEWQqqqFffIiTETENWwwOWEeeeeeeACMmTQFfOWLWVvvvvFQqqqqYOWOooOWOYOYQOWO_O_W_O_W_O_W_O_WO_WO_O_O_O_O_O_OR_R_R_R_R_R_R_R_R_R_R_R_R_R_R_R_R_R_R_R_R_R_R_R_R_RY_YyyyySUuuOSISO_S_S_SOPpSOKO_KO_KCcDKWDB_B_____________________________________________
Core #1 schedule: KkLWSFUQPDddddddddXxSUSVRJWKkRNJBWUWwwTttGgRNKkkRWNTtFRWKkRNWUuuGULRFSRSYKkkkRYAYFffGSRYHRYHNWMDddddddddRYGgggggYHNWK_YAHYNnGYSNHWwwwwSWSNKSYyyWKNNWKNNGAKWGggNnNW_NNWE_E_EF__________________________________________________
And now with -exit_if_fraction_left 0.05, where we lose (1567052521 -
1564522227)/1567052521. = 0.16% of the instructions but drastically
reduce the tail from 14% of the time to less than 1% of the time:
1564522227 instructions
120512812 idles
92.85% cpu busy by record count
96.39% cpu busy by time
97.46% cpu busy by time, ignoring idle past last instr
766.85user 6.33system 1:15.88elapsed 1018%CPU (0avgtext+0avgdata 4947364maxresident)k
Core #0 schedule: CccccccOXHKYEGGETRARrrPRTVvvvRrrNWwwOOKWVRRrPBbbXUVvvvvvOWKVLWVvvJjSOWKVUuTIiiiFPpppKAaaMFfffAHOKWAaGNBOWKAPPOABCWKPWOKWPCXxxxZOWKCccJSOSWKJUYRCOWKCcSOSUKkkkOROK_O_O_O_O_O
Core #1 schedule: KkLWSMmmFLSFffffffJjWBbGBUuuuuuuuuuuBDBJJRJWKkRNJWMBKkkRNWKkRNWKkkkRNWXxxxxxZOooAaUIiTHhhhSDNnnnHZzQNnnRNWXxxxxxRNWUuuRNWKXUuXRNKRWKNXxxRWKONNHRKWONURKWXRKXRKNW_KR_KkRK_KRKR_R_R_R_R_R_R_R_R_R_R_R__R__R__R___R___R___R___R___R
Fixes #6959
derekbruening
commented
Oct 3, 2024
brettcoon
approved these changes
Oct 3, 2024
…lying on defaults
…efault match CLI; print inputs left; augment comments; improve atomic assert
derekbruening
added a commit
that referenced
this pull request
Oct 4, 2024
Adds a new scheduler feature and CLI option exit_if_fraction_inputs_left. This
applies to -core_sharded and -core_serial modes. When an input reaches
EOF, if the number of non-EOF inputs left as a fraction of the original
inputs is equal to or less than this value then the scheduler exits
(sets all outputs to EOF) rather than finishing off the final inputs.
This helps avoid long sequences of idles during staggered endings with
fewer inputs left than cores and only a small fraction of the total
instructions left in those inputs.
The default value in scheduler_options_t and the CLI option is 0.05 (i.e., 5%),
which when tested on an large internal trace helps eliminate much of the
final idle time from the cores without losing many instructions.
Compare the numbers below for today's default with a long idle time and
so distinct differences between the "cpu busy by time" and "cpu busy by
time, ignoring idle past last instr" stats on a 39-core schedule-stats
run of a moderately large trace, with key stats and the 1st 2 cores (for
brevity) shown here:
```
1567052521 instructions
878027975 idles
64.09% cpu busy by record count
82.38% cpu busy by time
96.81% cpu busy by time, ignoring idle past last instr
Core #0 schedule: CccccccOXHhUuuuuAaSEOGOWEWQqqqFffIiTETENWwwOWEeeeeeeACMmTQFfOWLWVvvvvFQqqqqYOWOooOWOYOYQOWO_O_W_O_W_O_W_O_WO_WO_O_O_O_O_O_OR_R_R_R_R_R_R_R_R_R_R_R_R_R_R_R_R_R_R_R_R_R_R_R_R_RY_YyyyySUuuOSISO_S_S_SOPpSOKO_KO_KCcDKWDB_B_____________________________________________
Core #1 schedule: KkLWSFUQPDddddddddXxSUSVRJWKkRNJBWUWwwTttGgRNKkkRWNTtFRWKkRNWUuuGULRFSRSYKkkkRYAYFffGSRYHRYHNWMDddddddddRYGgggggYHNWK_YAHYNnGYSNHWwwwwSWSNKSYyyWKNNWKNNGAKWGggNnNW_NNWE_E_EF__________________________________________________
```
And now with -exit_if_fraction_inputs_left 0.05, where we lose (1567052521 -
1564522227)/1567052521. = 0.16% of the instructions but drastically
reduce the tail from 14% of the time to less than 1% of the time:
```
1564522227 instructions
120512812 idles
92.85% cpu busy by record count
96.39% cpu busy by time
97.46% cpu busy by time, ignoring idle past last instr
Core #0 schedule: CccccccOXHKYEGGETRARrrPRTVvvvRrrNWwwOOKWVRRrPBbbXUVvvvvvOWKVLWVvvJjSOWKVUuTIiiiFPpppKAaaMFfffAHOKWAaGNBOWKAPPOABCWKPWOKWPCXxxxZOWKCccJSOSWKJUYRCOWKCcSOSUKkkkOROK_O_O_O_O_O
Core #1 schedule: KkLWSMmmFLSFffffffJjWBbGBUuuuuuuuuuuBDBJJRJWKkRNJWMBKkkRNWKkRNWKkkkRNWXxxxxxZOooAaUIiTHhhhSDNnnnHZzQNnnRNWXxxxxxRNWUuuRNWKXUuXRNKRWKNXxxRWKONNHRKWONURKWXRKXRKNW_KR_KkRK_KRKR_R_R_R_R_R_R_R_R_R_R_R__R__R__R___R___R___R___R___R
```
Fixes #6959
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Adds a new scheduler feature and CLI option exit_if_fraction_left. This applies to -core_sharded and -core_serial modes. When an input reaches EOF, if the number of non-EOF inputs left as a fraction of the original inputs is equal to or less than this value then the scheduler exits (sets all outputs to EOF) rather than finishing off the final inputs. This helps avoid long sequences of idles during staggered endings with fewer inputs left than cores and only a small fraction of the total instructions left in those inputs.
The default value in scheduler_options_t is 0 as simulators are typically already choosing to stop at some even point. For analyzers, however, via the command-line option, the default is 0.05 (i.e., 5%), which when tested on an large internal trace helps eliminate much of the final idle time from the cores (just about any value over 0.05 works well: it is not overly sensitive).
Compare the numbers below for today's default with a long idle time and so distinct differences between the "cpu busy by time" and "cpu busy by time, ignoring idle past last instr" stats on a 39-core schedule-stats run of a moderately large trace, with key stats and the 1st 2 cores (for brevity) shown here:
And now with -exit_if_fraction_left 0.05, where we lose (1567052521 - 1564522227)/1567052521. = 0.16% of the instructions but drastically reduce the tail from 14% of the time to less than 1% of the time:
Fixes #6959