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| author | Stafford Horne <shorne@gmail.com> | 2016-03-21 16:16:46 +0900 |
|---|---|---|
| committer | Stafford Horne <shorne@gmail.com> | 2017-02-25 04:14:36 +0900 |
| commit | f5d45dc9116b17ee830d3425ece1e9485c9bab88 (patch) | |
| tree | 1ad140d3860d795bf9e425d1aa5d34faf0514c22 /arch/openrisc/TODO.openrisc | |
| parent | d857a1e253498feb231173218df26f5562c70f09 (diff) | |
| download | linux-f5d45dc9116b17ee830d3425ece1e9485c9bab88.tar.gz linux-f5d45dc9116b17ee830d3425ece1e9485c9bab88.tar.xz | |
openrisc: Add optimized memcpy routine
The generic memcpy routine provided in kernel does only byte copies.
Using word copies we can lower boot time and cycles spend in memcpy
quite significantly.
Booting on my de0 nano I see boot times go from 7.2 to 5.6 seconds.
The avg cycles in memcpy during boot go from 6467 to 1887.
I tested several algorithms (see code in previous patch mails)
The implementations I tested and avg cycles:
- Word Copies + Loop Unrolls + Non Aligned 1882
- Word Copies + Loop Unrolls 1887
- Word Copies 2441
- Byte Copies + Loop Unrolls 6467
- Byte Copies 7600
In the end I ended up going with Word Copies + Loop Unrolls as it
provides best tradeoff between simplicity and boot speedups.
Signed-off-by: Stafford Horne <shorne@gmail.com>
Diffstat (limited to 'arch/openrisc/TODO.openrisc')
| -rw-r--r-- | arch/openrisc/TODO.openrisc | 1 |
1 files changed, 0 insertions, 1 deletions
diff --git a/arch/openrisc/TODO.openrisc b/arch/openrisc/TODO.openrisc index 0eb04c8240f9..c43d4e1d14eb 100644 --- a/arch/openrisc/TODO.openrisc +++ b/arch/openrisc/TODO.openrisc @@ -10,4 +10,3 @@ that are due for investigation shortly, i.e. our TODO list: or1k and this change is slowly trickling through the stack. For the time being, or32 is equivalent to or1k. --- Implement optimized version of memcpy and memset |