Transaction Commitment Timestamp generator for a thousand cores
The basic idea is to create and deliver timestamps for client transactions on the order of a billion timestamp requests per second. The generator must have an extremely short execution path that doesn't require atomic operations for every request.
#ifdef SCAN
printf("Table Scan\n");
#endif
#ifdef QUEUE
printf("FIFO Queue\n");
#endif
#ifdef ATOMIC
printf("Atomic Incr\n");
#endif
#ifdef ALIGN
printf("Atomic Aligned 64\n");
#endif
#ifdef RDTSC
printf("TSC COUNT: New Epochs = %" PRIu64 "\n", rdtscEpochs);
#endif
#ifdef CLOCK
printf("Hi Res Timer\n");
#endif
As a baseline here are the timing results for one billion requests for a new timestamp using an atomic increment of a single common timestamp by threads 1 thru 7 concurrently.
No contention, 1 thread:
------------------------
Hi-Performance-Timestamps\timestamps>standalone.exe 1 1000000000
thread 1 launched for 1000000000 timestamps
Begin client 1
Atomic Incr
real 0m6.260s -- 6ns per timestamp
user 0m6.250s
sys 0m0.000s
2 threads:
------------------------
Hi-Performance-Timestamps\timestamps>standalone.exe 2 500000000
thread 1 launched for 500000000 timestamps
thread 2 launched for 500000000 timestamps
Begin client 1
Begin client 2
Atomic Incr
real 0m20.167s -- 20ns
user 0m40.250s
sys 0m0.000s
3 threads:
------------------------
Hi-Performance-Timestamps\timestamps>standalone.exe 3 333333333
thread 1 launched for 333333333 timestamps
thread 2 launched for 333333333 timestamps
Begin client 2
Begin client 3
thread 3 launched for 333333333 timestamps
Begin client 1
Atomic Incr
real 0m25.531s
user 1m16.437s
sys 0m0.000s
4 threads:
------------------------
Hi-Performance-Timestamps\timestamps>standalone.exe 4 250000000
thread 1 launched for 250000000 timestamps
thread 2 launched for 250000000 timestamps
thread 3 launched for 250000000 timestamps
Begin client 2
Begin client 3
thread 4 launched for 250000000 timestamps
Begin client 1
Begin client 4
Atomic Incr
real 0m18.416s
user 1m12.437s
sys 0m0.000s
5 threads:
------------------------
Hi-Performance-Timestamps\timestamps>standalone.exe 5 200000000
thread 1 launched for 200000000 timestamps
thread 2 launched for 200000000 timestamps
Begin client 1
Begin client 2
thread 3 launched for 200000000 timestamps
Begin client 3
thread 4 launched for 200000000 timestamps
Begin client 4
thread 5 launched for 200000000 timestamps
Begin client 5
Atomic Incr
real 0m24.651s
user 2m2.343s
sys 0m0.000s
6 threads:
------------------------
Hi-Performance-Timestamps\timestamps>standalone.exe 6 166666666
thread 1 launched for 166666666 timestamps
thread 2 launched for 166666666 timestamps
Begin client 1
Begin client 2
thread 3 launched for 166666666 timestamps
Begin client 3
thread 4 launched for 166666666 timestamps
Begin client 4
Begin client 5
thread 5 launched for 166666666 timestamps
thread 6 launched for 166666666 timestamps
Begin client 6
Atomic Incr
real 0m24.008s
user 2m22.546s
sys 0m0.000s
7 threads:
------------------------
Hi-Performance-Timestamps\timestamps>standalone.exe 7 142857145
thread 1 launched for 142857145 timestamps
thread 2 launched for 142857145 timestamps
Begin client 2
Begin client 1
thread 3 launched for 142857145 timestamps
Begin client 3
thread 4 launched for 142857145 timestamps
Begin client 4
thread 5 launched for 142857145 timestamps
Begin client 5
thread 6 launched for 142857145 timestamps
Begin client 6
thread 7 launched for 142857145 timestamps
Begin client 7
Atomic Incr
real 0m25.329s
user 2m53.109s
sys 0m0.047s
One answer to this deteriorating situation is to derive each timestamp value from the RDTSC hardware counter, grouping them into 1 second long Epochs of 1 billion timestamps.
C:cl /Oxib2 /D RDTSC standalone.c timestamps.c
Microsoft (R) C/C++ Optimizing Compiler Version 19.23.28106.4 for x64
Copyright (C) Microsoft Corporation. All rights reserved.
standalone.c
timestamps.c
Generating Code...
Microsoft (R) Incremental Linker Version 14.23.28106.4
Copyright (C) Microsoft Corporation. All rights reserved.
/out:standalone.exe
standalone.obj
timestamps.obj
C:standalone 1 1000000000
size of Timestamp = 8, TsEpoch = 16
RDTSC timing = 7ns, resolution = 25
thread 1 launched for 1000000000 timestamps
Begin client 1
client 1 count = 1000000000 Out of Order = 0 dups = 0
TSC COUNT: New Epochs = 2
real 0m13.127s
user 0m13.125s
sys 0m0.000s
C:standalone 2 500000000
size of Timestamp = 8, TsEpoch = 16
RDTSC timing = 7ns, resolution = 26
thread 1 launched for 500000000 timestamps
thread 2 launched for 500000000 timestamps
Begin client 1
Begin client 2
client 2 count = 500000000 Out of Order = 0 dups = 0
client 1 count = 500000000 Out of Order = 0 dups = 0
TSC COUNT: New Epochs = 0
real 0m6.659s
user 0m13.296s
sys 0m0.000s
C:standalone 3 333333333
size of Timestamp = 8, TsEpoch = 16
RDTSC timing = 7ns, resolution = 25
thread 1 launched for 333333333 timestamps
thread 2 launched for 333333333 timestamps
thread 3 launched for 333333333 timestamps
Begin client 2
Begin client 3
Begin client 1
client 3 count = 333333333 Out of Order = 0 dups = 0
client 2 count = 333333333 Out of Order = 0 dups = 0
client 1 count = 333333333 Out of Order = 0 dups = 0
TSC COUNT: New Epochs = 6
real 0m18.723s
user 0m55.500s
sys 0m0.000s
C:standalone 4 250000000
size of Timestamp = 8, TsEpoch = 16
RDTSC timing = 7ns, resolution = 25
thread 1 launched for 250000000 timestamps
thread 2 launched for 250000000 timestamps
thread 3 launched for 250000000 timestamps
Begin client 1
thread 4 launched for 250000000 timestamps
Begin client 2
Begin client 3
Begin client 4
client 1 count = 250000000 Out of Order = 0 dups = 0
client 4 count = 250000000 Out of Order = 0 dups = 0
client 2 count = 250000000 Out of Order = 0 dups = 0
client 3 count = 250000000 Out of Order = 0 dups = 0
TSC COUNT: New Epochs = 7
real 0m17.298s
user 1m2.875s
sys 0m0.000s
C:standalone 5 200000000
size of Timestamp = 8, TsEpoch = 16
RDTSC timing = 7ns, resolution = 25
thread 1 launched for 200000000 timestamps
thread 2 launched for 200000000 timestamps
thread 3 launched for 200000000 timestamps
Begin client 1
Begin client 2
thread 4 launched for 200000000 timestamps
Begin client 3
Begin client 4
thread 5 launched for 200000000 timestamps
Begin client 5
client 4 count = 200000000 Out of Order = 0 dups = 0
client 5 count = 200000000 Out of Order = 0 dups = 0
client 1 count = 200000000 Out of Order = 0 dups = 0
client 2 count = 200000000 Out of Order = 0 dups = 0
client 3 count = 200000000 Out of Order = 0 dups = 0
TSC COUNT: New Epochs = 10
real 0m13.627s
user 1m7.109s
sys 0m0.000s
C:standalone 6 166666666
size of Timestamp = 8, TsEpoch = 16
RDTSC timing = 7ns, resolution = 26
thread 1 launched for 166666666 timestamps
thread 2 launched for 166666666 timestamps
thread 3 launched for 166666666 timestamps
thread 4 launched for 166666666 timestamps
Begin client 1
thread 5 launched for 166666666 timestamps
Begin client 3
Begin client 2
thread 6 launched for 166666666 timestamps
Begin client 4
Begin client 5
Begin client 6
client 2 count = 166666666 Out of Order = 0 dups = 0
client 1 count = 166666666 Out of Order = 0 dups = 0
client 3 count = 166666666 Out of Order = 0 dups = 0
client 5 count = 166666666 Out of Order = 0 dups = 0
client 4 count = 166666666 Out of Order = 0 dups = 0
client 6 count = 166666666 Out of Order = 0 dups = 0
TSC COUNT: New Epochs = 6
real 0m12.804s
user 1m13.750s
sys 0m0.000s
C:standalone 7 142800000
size of Timestamp = 8, TsEpoch = 16
RDTSC timing = 7ns, resolution = 25
thread 1 launched for 142800000 timestamps
thread 2 launched for 142800000 timestamps
Begin client 1
Begin client 2
thread 3 launched for 142800000 timestamps
Begin client 3
thread 4 launched for 142800000 timestamps
Begin client 4
thread 5 launched for 142800000 timestamps
Begin client 5
thread 6 launched for 142800000 timestamps
Begin client 6
thread 7 launched for 142800000 timestamps
Begin client 7
client 1 count = 142800000 Out of Order = 0 dups = 0
client 2 count = 142800000 Out of Order = 0 dups = 0
client 4 count = 142800000 Out of Order = 0 dups = 0
client 7 count = 142800000 Out of Order = 0 dups = 0
client 6 count = 142800000 Out of Order = 0 dups = 0
client 3 count = 142800000 Out of Order = 0 dups = 0
client 5 count = 142800000 Out of Order = 0 dups = 0
TSC COUNT: New Epochs = 12
real 0m14.039s
user 1m27.031s
sys 0m0.000s
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