available and if that is true make use of them.
Thank you very much to Andrew Turner for providing help and review the patch!
Reviewed by: andrew
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D10499
Derived from an implementation by Mark Adler.
The fast loop performs three simultaneous CRCs over subsets of the data
before composing them. This takes advantage of certain properties of
the CRC32 implementation in Intel hardware. (The CRC instruction takes 1
cycle but has 2-3 cycles of latency.)
The CRC32 instruction does not manipulate FPU state.
i386 does not have the crc32q instruction, so avoid it there. Otherwise
the implementation is identical to amd64.
Add basic userland tests to verify correctness on a variety of inputs.
PR: 216467
Reported by: Ben RUBSON <ben.rubson at gmail.com>
Reviewed by: kib@, markj@ (earlier version)
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D9342
longer do we require SCTP to be in the kernel for the
lib to be able to handle SCTP. We do this by moving
the CRC32c checksum into libkern/crc32.c and then adjusting
all routines to use the common methods. Note that this
will improve the performance of iSCSI since they were
using the old single 256 bit table lookup versus the
slicing 8 algorithm (which gives a 4x speed up in
CRC32c calculation :-D)
Reviewed by:rwatson, gnn, scottl, paolo
MFC after: 4 week? (assuming we MFC the alias_sctp changes)
CRC logic to a new function: crc32_raw() that obtains the initial
CRC value as well as leaves any post-processing to the caller. As
such, it can be used when the initial CRC value is not ~0U or when
the final CRC value does need to be inverted (bitwise). It also
means that crc32_raw() can be called repeatedly when the data is
not available as a single block, such as for scatter/gather lists
and the likes.
Avoid the additional call overhead incured by the refactoring by
moving the implementation off crc32() to sys/systm.h and making it
inlinable. Since crc32_raw() is itself trivial and since it may
be used in loops that iterate over fragments, having it available
for inlining can be beneficial. Hence, move its implementation
to sys/systm.h as well.
Keep the original implementation of crc32() in libkern/crc32.c for
documentation purposes (as a comment of course).
Triggered by: Jose M Rodriguez (josemi at freebsd dot jazztel dot es)
Discussed on: current@
Tested on: amd64, ia64 (BVO having GPT partitions)
Jargon file candidate: BVO = By Virtue Of :-)
