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Description
Description of defect
Following investigations in #12116 , it turns out that division with microlib seems much slower than ARM lib (and possibly also other libs) on cores like cortex-M0.
Few measurement on a "divided by 1000" operation were measured and are reported here for background information:
Board | Toolchain | Division | Operation time (incl. IOs toggling) | Frequency during wake-up |
---|---|---|---|---|
L476RG | uARM | Native ( / ) | 440ns | 48MHz |
L476RG | uARM | Div1000 | 480ns | 48MHz |
L476RG | ARMC6 | Native ( / ) | 440ns | 48MHz |
L476RG | ARMC6 | Div1000 | 480ns | 48MHz |
L073RZ | uARM | Native ( / ) | 86µs | 4MHz |
L073RZ | uARM | Div1000 | 226µs | 4MHz |
L073RZ | uARM | Div10 (3 times) | 18µs | 4MHz |
L073RZ | ARMC6 | Native ( / ) | 11,6µs | 4MHz |
L073RZ | ARMC6 | Div1000 | 13µs | 4MHz |
L073RZ | ARMC6 | Div10 (3 times) | 18µs | 4MHz |
Target(s) affected by this defect ?
ALL
Toolchain(s) (name and version) displaying this defect ?
microlib toolchain (µARM)
What version of Mbed-os are you using (tag or sha) ?
mbed-os master of Jan 2020.
What version(s) of tools are you using. List all that apply (E.g. mbed-cli)
Not relevant here.
How is this defect reproduced ?
See detailed history in #12116