performance gain on SSE2 is approx. 20-25%. altivec
is not tested. performance for unsigned long arithmetic
is unchanged.
Signed-off-by: Peter Lieven <pl@kamp.de>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Orit Wasserman <owasserm@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
this adds buffer_find_nonzero_offset() which is a SSE2/Altivec
optimized function that searches for non-zero content in a
buffer.
the function starts full unrolling only after the first few chunks have
been checked one by one. analyzing real memory page data has revealed
that non-zero pages are non-zero within the first 256-512 bits in
most cases. as this function is also heavily used to check for zero memory
pages this tweak has been made to avoid the high setup costs of the fully
unrolled check for non-zero pages.
due to the optimizations used in the function there are restrictions
on buffer address and search length. the function
can_use_buffer_find_nonzero_content() can be used to check if
the function can be used safely.
Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Juan Quintela <quintela@redhat.com>
There are lots of duplicate parsing code using strto*() in QEMU, and
most of that code is broken in one way or another. Even the visitors
code have duplicate integer parsing code[1]. This introduces functions
to help parsing unsigned int values: parse_uint() and parse_uint_full().
Parsing functions for signed ints and floats will be submitted later.
parse_uint_full() has all the checks made by opts_type_uint64() at
opts-visitor.c:
- Check for NULL (returns -EINVAL)
- Check for negative numbers (returns -EINVAL)
- Check for empty string (returns -EINVAL)
- Check for overflow or other errno values set by strtoll() (returns
-errno)
- Check for end of string (reject invalid characters after number)
(returns -EINVAL)
parse_uint() does everything above except checking for the end of the
string, so callers can continue parsing the remainder of string after
the number.
Unit tests included.
[1] string-input-visitor.c:parse_int() could use the same parsing code
used by opts-visitor.c:opts_type_int(), instead of duplicating that
logic.
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
