The patch titled
Subject: xxHash: create arch dependent 32/64-bit xxhash()
has been removed from the -mm tree. Its filename was
xxhash-create-arch-dependent-32-64-bit-xxhash.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Timofey Titovets <nefelim4ag@xxxxxxxxx>
Subject: xxHash: create arch dependent 32/64-bit xxhash()
Patch series "Currently used jhash are slow enough and replace it allow as
to make KSM", v8.
Apeed (in kernel):
ksm: crc32c hash() 12081 MB/s
ksm: xxh64 hash() 8770 MB/s
ksm: xxh32 hash() 4529 MB/s
ksm: jhash2 hash() 1569 MB/s
Sioh Lee's testing (copy from other mail):
Test platform: openstack cloud platform (NEWTON version)
Experiment node: openstack based cloud compute node (CPU: xeon E5-2620 v3, memory 64gb)
VM: (2 VCPU, RAM 4GB, DISK 20GB) * 4
Linux kernel: 4.14 (latest version)
KSM setup - sleep_millisecs: 200ms, pages_to_scan: 200
Experiment process:
Firstly, we turn off KSM and launch 4 VMs. Then we turn on the KSM and
measure the checksum computation time until full_scans become two.
The experimental results (the experimental value is the average of the measured values)
crc32c_intel: 1084.10ns
crc32c (no hardware acceleration): 7012.51ns
xxhash32: 2227.75ns
xxhash64: 1413.16ns
jhash2: 5128.30ns
In summary, the result shows that crc32c_intel has advantages over all of
the hash function used in the experiment. (decreased by 84.54% compared
to crc32c, 78.86% compared to jhash2, 51.33% xxhash32, 23.28% compared to
xxhash64) the results are similar to those of Timofey.
But, use only xxhash for now, because for using crc32c, cryptoapi must be
initialized first - that require some tricky solution to work good in all
situations.
So:
- First patch implement compile time pickup of fastest implementation of
xxhash for target platform.
- The second patch replaces jhash2 with xxhash
This patch (of 2):
xxh32() - fast on both 32/64-bit platforms
xxh64() - fast only on 64-bit platform
Create xxhash() which will pick up the fastest version at compile time.
Link: http://lkml.kernel.org/r/20181023182554.23464-2-nefelim4ag@xxxxxxxxx
Signed-off-by: Timofey Titovets <nefelim4ag@xxxxxxxxx>
Reviewed-by: Pavel Tatashin <pavel.tatashin@xxxxxxxxxxxxx>
Reviewed-by: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: leesioh <solee@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/include/linux/xxhash.h~xxhash-create-arch-dependent-32-64-bit-xxhash
+++ a/include/linux/xxhash.h
@@ -107,6 +107,29 @@ uint32_t xxh32(const void *input, size_t
*/
uint64_t xxh64(const void *input, size_t length, uint64_t seed);
+/**
+ * xxhash() - calculate wordsize hash of the input with a given seed
+ * @input: The data to hash.
+ * @length: The length of the data to hash.
+ * @seed: The seed can be used to alter the result predictably.
+ *
+ * If the hash does not need to be comparable between machines with
+ * different word sizes, this function will call whichever of xxh32()
+ * or xxh64() is faster.
+ *
+ * Return: wordsize hash of the data.
+ */
+
+static inline unsigned long xxhash(const void *input, size_t length,
+ uint64_t seed)
+{
+#if BITS_PER_LONG == 64
+ return xxh64(input, length, seed);
+#else
+ return xxh32(input, length, seed);
+#endif
+}
+
/*-****************************
* Streaming Hash Functions
*****************************/
_
Patches currently in -mm which might be from nefelim4ag@xxxxxxxxx are
