On Tue, Sep 12, 2017 at 7:05 PM, Felix Kuehling <Felix.Kuehling at amd.com> wrote:
> This adds a statically sized closed hash table implementation with
> low memory and CPU overhead. The API is inspired by kfifo.
>
> Storing, retrieving and deleting data does not involve any dynamic
> memory management, which makes it ideal for use in interrupt context.
> Static memory usage per entry comprises a 32 or 64 bit hash key, two
> bits for occupancy tracking and the value size stored in the table.
> No list heads or pointers are needed. Therefore this data structure
> should be quite cache-friendly, too.
>
> It uses linear probing and lazy deletion. During lookups free space
> is reclaimed and entries relocated to speed up future lookups.
>
> Signed-off-by: Felix Kuehling <Felix.Kuehling at amd.com>
> Acked-by: Christian König <christian.koenig at amd.com>
Acked-by: Alex Deucher <alexander.deucher at amd.com>
> ---
> drivers/gpu/drm/Kconfig | 2 +
> drivers/gpu/drm/Makefile | 1 +
> drivers/gpu/drm/amd/include/linux/chash.h | 358 +++++++++++++++++
> drivers/gpu/drm/amd/lib/Kconfig | 27 ++
> drivers/gpu/drm/amd/lib/Makefile | 11 +
> drivers/gpu/drm/amd/lib/chash.c | 622 ++++++++++++++++++++++++++++++
> 6 files changed, 1021 insertions(+)
> create mode 100644 drivers/gpu/drm/amd/include/linux/chash.h
> create mode 100644 drivers/gpu/drm/amd/lib/Kconfig
> create mode 100644 drivers/gpu/drm/amd/lib/Makefile
> create mode 100644 drivers/gpu/drm/amd/lib/chash.c
>
> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
> index 83cb2a8..1989c27 100644
> --- a/drivers/gpu/drm/Kconfig
> +++ b/drivers/gpu/drm/Kconfig
> @@ -191,6 +191,8 @@ config DRM_AMDGPU
>
> source "drivers/gpu/drm/amd/amdgpu/Kconfig"
>
> +source "drivers/gpu/drm/amd/lib/Kconfig"
> +
> source "drivers/gpu/drm/nouveau/Kconfig"
>
> source "drivers/gpu/drm/i915/Kconfig"
> diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
> index 24a066e..74683b7 100644
> --- a/drivers/gpu/drm/Makefile
> +++ b/drivers/gpu/drm/Makefile
> @@ -52,6 +52,7 @@ obj-$(CONFIG_DRM_ARM) += arm/
> obj-$(CONFIG_DRM_TTM) += ttm/
> obj-$(CONFIG_DRM_TDFX) += tdfx/
> obj-$(CONFIG_DRM_R128) += r128/
> +obj-y += amd/lib/
> obj-$(CONFIG_HSA_AMD) += amd/amdkfd/
> obj-$(CONFIG_DRM_RADEON)+= radeon/
> obj-$(CONFIG_DRM_AMDGPU)+= amd/amdgpu/
> diff --git a/drivers/gpu/drm/amd/include/linux/chash.h b/drivers/gpu/drm/amd/include/linux/chash.h
> new file mode 100644
> index 0000000..c89b92b
> --- /dev/null
> +++ b/drivers/gpu/drm/amd/include/linux/chash.h
> @@ -0,0 +1,358 @@
> +/*
> + * Copyright 2017 Advanced Micro Devices, Inc.
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> + * copy of this software and associated documentation files (the "Software"),
> + * to deal in the Software without restriction, including without limitation
> + * the rights to use, copy, modify, merge, publish, distribute, sublicense,
> + * and/or sell copies of the Software, and to permit persons to whom the
> + * Software is furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice shall be included in
> + * all copies or substantial portions of the Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
> + * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
> + * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
> + * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
> + * OTHER DEALINGS IN THE SOFTWARE.
> + *
> + */
> +
> +#ifndef _LINUX_CHASH_H
> +#define _LINUX_CHASH_H
> +
> +#include <linux/types.h>
> +#include <linux/hash.h>
> +#include <linux/bug.h>
> +#include <linux/bitops.h>
> +
> +struct __chash_table {
> + u8 bits;
> + u8 key_size;
> + unsigned int value_size;
> + u32 size_mask;
> + unsigned long *occup_bitmap, *valid_bitmap;
> + union {
> + u32 *keys32;
> + u64 *keys64;
> + };
> + u8 *values;
> +
> +#ifdef CONFIG_CHASH_STATS
> + u64 hits, hits_steps, hits_time_ns;
> + u64 miss, miss_steps, miss_time_ns;
> + u64 relocs, reloc_dist;
> +#endif
> +};
> +
> +#define __CHASH_BITMAP_SIZE(bits) \
> + (((1 << (bits)) + BITS_PER_LONG - 1) / BITS_PER_LONG)
> +#define __CHASH_ARRAY_SIZE(bits, size) \
> + ((((size) << (bits)) + sizeof(long) - 1) / sizeof(long))
> +
> +#define __CHASH_DATA_SIZE(bits, key_size, value_size) \
> + (__CHASH_BITMAP_SIZE(bits) * 2 + \
> + __CHASH_ARRAY_SIZE(bits, key_size) + \
> + __CHASH_ARRAY_SIZE(bits, value_size))
> +
> +#define STRUCT_CHASH_TABLE(bits, key_size, value_size) \
> + struct { \
> + struct __chash_table table; \
> + unsigned long data \
> + [__CHASH_DATA_SIZE(bits, key_size, value_size)];\
> + }
> +
> +/**
> + * struct chash_table - Dynamically allocated closed hash table
> + *
> + * Use this struct for dynamically allocated hash tables (using
> + * chash_table_alloc and chash_table_free), where the size is
> + * determined at runtime.
> + */
> +struct chash_table {
> + struct __chash_table table;
> + unsigned long *data;
> +};
> +
> +/**
> + * DECLARE_CHASH_TABLE - macro to declare a closed hash table
> + * @table: name of the declared hash table
> + * @bts: Table size will be 2^bits entries
> + * @key_sz: Size of hash keys in bytes, 4 or 8
> + * @val_sz: Size of data values in bytes, can be 0
> + *
> + * This declares the hash table variable with a static size.
> + *
> + * The closed hash table stores key-value pairs with low memory and
> + * lookup overhead. In operation it performs no dynamic memory
> + * management. The data being stored does not require any
> + * list_heads. The hash table performs best with small @val_sz and as
> + * long as some space (about 50%) is left free in the table. But the
> + * table can still work reasonably efficiently even when filled up to
> + * about 90%. If bigger data items need to be stored and looked up,
> + * store the pointer to it as value in the hash table.
> + *
> + * @val_sz may be 0. This can be useful when all the stored
> + * information is contained in the key itself and the fact that it is
> + * in the hash table (or not).
> + */
> +#define DECLARE_CHASH_TABLE(table, bts, key_sz, val_sz) \
> + STRUCT_CHASH_TABLE(bts, key_sz, val_sz) table
> +
> +#ifdef CONFIG_CHASH_STATS
> +#define __CHASH_STATS_INIT(prefix), \
> + prefix.hits = 0, \
> + prefix.hits_steps = 0, \
> + prefix.hits_time_ns = 0, \
> + prefix.miss = 0, \
> + prefix.miss_steps = 0, \
> + prefix.miss_time_ns = 0, \
> + prefix.relocs = 0, \
> + prefix.reloc_dist = 0
> +#else
> +#define __CHASH_STATS_INIT(prefix)
> +#endif
> +
> +#define __CHASH_TABLE_INIT(prefix, data, bts, key_sz, val_sz) \
> + prefix.bits = (bts), \
> + prefix.key_size = (key_sz), \
> + prefix.value_size = (val_sz), \
> + prefix.size_mask = ((1 << bts) - 1), \
> + prefix.occup_bitmap = &data[0], \
> + prefix.valid_bitmap = &data \
> + [__CHASH_BITMAP_SIZE(bts)], \
> + prefix.keys64 = (u64 *)&data \
> + [__CHASH_BITMAP_SIZE(bts) * 2], \
> + prefix.values = (u8 *)&data \
> + [__CHASH_BITMAP_SIZE(bts) * 2 + \
> + __CHASH_ARRAY_SIZE(bts, key_sz)] \
> + __CHASH_STATS_INIT(prefix)
> +
> +/**
> + * DEFINE_CHASH_TABLE - macro to define and initialize a closed hash table
> + * @tbl: name of the declared hash table
> + * @bts: Table size will be 2^bits entries
> + * @key_sz: Size of hash keys in bytes, 4 or 8
> + * @val_sz: Size of data values in bytes, can be 0
> + *
> + * Note: the macro can be used for global and local hash table variables.
> + */
> +#define DEFINE_CHASH_TABLE(tbl, bts, key_sz, val_sz) \
> + DECLARE_CHASH_TABLE(tbl, bts, key_sz, val_sz) = { \
> + .table = { \
> + __CHASH_TABLE_INIT(, (tbl).data, bts, key_sz, val_sz) \
> + }, \
> + .data = {0} \
> + }
> +
> +/**
> + * INIT_CHASH_TABLE - Initialize a hash table declared by DECLARE_CHASH_TABLE
> + * @tbl: name of the declared hash table
> + * @bts: Table size will be 2^bits entries
> + * @key_sz: Size of hash keys in bytes, 4 or 8
> + * @val_sz: Size of data values in bytes, can be 0
> + */
> +#define INIT_CHASH_TABLE(tbl, bts, key_sz, val_sz) \
> + __CHASH_TABLE_INIT(((tbl).table), (tbl).data, bts, key_sz, val_sz)
> +
> +int chash_table_alloc(struct chash_table *table, u8 bits, u8 key_size,
> + unsigned int value_size, gfp_t gfp_mask);
> +void chash_table_free(struct chash_table *table);
> +
> +/**
> + * chash_table_dump_stats - Dump statistics of a closed hash table
> + * @tbl: Pointer to the table structure
> + *
> + * Dumps some performance statistics of the table gathered in operation
> + * in the kernel log using pr_debug. If CONFIG_DYNAMIC_DEBUG is enabled,
> + * user must turn on messages for chash.c (file chash.c +p).
> + */
> +#ifdef CONFIG_CHASH_STATS
> +#define chash_table_dump_stats(tbl) __chash_table_dump_stats(&(*tbl).table)
> +
> +void __chash_table_dump_stats(struct __chash_table *table);
> +#else
> +#define chash_table_dump_stats(tbl)
> +#endif
> +
> +/**
> + * chash_table_reset_stats - Reset statistics of a closed hash table
> + * @tbl: Pointer to the table structure
> + */
> +#ifdef CONFIG_CHASH_STATS
> +#define chash_table_reset_stats(tbl) __chash_table_reset_stats(&(*tbl).table)
> +
> +static inline void __chash_table_reset_stats(struct __chash_table *table)
> +{
> + (void)table __CHASH_STATS_INIT((*table));
> +}
> +#else
> +#define chash_table_reset_stats(tbl)
> +#endif
> +
> +/**
> + * chash_table_copy_in - Copy a new value into the hash table
> + * @tbl: Pointer to the table structure
> + * @key: Key of the entry to add or update
> + * @value: Pointer to value to copy, may be NULL
> + *
> + * If @key already has an entry, its value is replaced. Otherwise a
> + * new entry is added. If @value is NULL, the value is left unchanged
> + * or uninitialized. Returns 1 if an entry already existed, 0 if a new
> + * entry was added or %-ENOMEM if there was no free space in the
> + * table.
> + */
> +#define chash_table_copy_in(tbl, key, value) \
> + __chash_table_copy_in(&(*tbl).table, key, value)
> +
> +int __chash_table_copy_in(struct __chash_table *table, u64 key,
> + const void *value);
> +
> +/**
> + * chash_table_copy_out - Copy a value out of the hash table
> + * @tbl: Pointer to the table structure
> + * @key: Key of the entry to find
> + * @value: Pointer to value to copy, may be NULL
> + *
> + * If @value is not NULL and the table has a non-0 value_size, the
> + * value at @key is copied to @value. Returns the slot index of the
> + * entry or %-EINVAL if @key was not found.
> + */
> +#define chash_table_copy_out(tbl, key, value) \
> + __chash_table_copy_out(&(*tbl).table, key, value, false)
> +
> +int __chash_table_copy_out(struct __chash_table *table, u64 key,
> + void *value, bool remove);
> +
> +/**
> + * chash_table_remove - Remove an entry from the hash table
> + * @tbl: Pointer to the table structure
> + * @key: Key of the entry to find
> + * @value: Pointer to value to copy, may be NULL
> + *
> + * If @value is not NULL and the table has a non-0 value_size, the
> + * value at @key is copied to @value. The entry is removed from the
> + * table. Returns the slot index of the removed entry or %-EINVAL if
> + * @key was not found.
> + */
> +#define chash_table_remove(tbl, key, value) \
> + __chash_table_copy_out(&(*tbl).table, key, value, true)
> +
> +/*
> + * Low level iterator API used internally by the above functions.
> + */
> +struct chash_iter {
> + struct __chash_table *table;
> + unsigned long mask;
> + int slot;
> +};
> +
> +/**
> + * CHASH_ITER_INIT - Initialize a hash table iterator
> + * @tbl: Pointer to hash table to iterate over
> + * @s: Initial slot number
> + */
> +#define CHASH_ITER_INIT(table, s) { \
> + table, \
> + 1UL << ((s) & (BITS_PER_LONG - 1)), \
> + s \
> + }
> +/**
> + * CHASH_ITER_SET - Set hash table iterator to new slot
> + * @iter: Iterator
> + * @s: Slot number
> + */
> +#define CHASH_ITER_SET(iter, s) \
> + (iter).mask = 1UL << ((s) & (BITS_PER_LONG - 1)), \
> + (iter).slot = (s)
> +/**
> + * CHASH_ITER_INC - Increment hash table iterator
> + * @table: Hash table to iterate over
> + *
> + * Wraps around at the end.
> + */
> +#define CHASH_ITER_INC(iter) do { \
> + (iter).mask = (iter).mask << 1 | \
> + (iter).mask >> (BITS_PER_LONG - 1); \
> + (iter).slot = ((iter).slot + 1) & (iter).table->size_mask; \
> + } while (0)
> +
> +static inline bool chash_iter_is_valid(const struct chash_iter iter)
> +{
> + BUG_ON((unsigned)iter.slot >= (1 << iter.table->bits));
> + return !!(iter.table->valid_bitmap[iter.slot >> _BITOPS_LONG_SHIFT] &
> + iter.mask);
> +}
> +static inline bool chash_iter_is_empty(const struct chash_iter iter)
> +{
> + BUG_ON((unsigned)iter.slot >= (1 << iter.table->bits));
> + return !(iter.table->occup_bitmap[iter.slot >> _BITOPS_LONG_SHIFT] &
> + iter.mask);
> +}
> +
> +static inline void chash_iter_set_valid(const struct chash_iter iter)
> +{
> + BUG_ON((unsigned)iter.slot >= (1 << iter.table->bits));
> + iter.table->valid_bitmap[iter.slot >> _BITOPS_LONG_SHIFT] |= iter.mask;
> + iter.table->occup_bitmap[iter.slot >> _BITOPS_LONG_SHIFT] |= iter.mask;
> +}
> +static inline void chash_iter_set_invalid(const struct chash_iter iter)
> +{
> + BUG_ON((unsigned)iter.slot >= (1 << iter.table->bits));
> + iter.table->valid_bitmap[iter.slot >> _BITOPS_LONG_SHIFT] &= ~iter.mask;
> +}
> +static inline void chash_iter_set_empty(const struct chash_iter iter)
> +{
> + BUG_ON((unsigned)iter.slot >= (1 << iter.table->bits));
> + iter.table->occup_bitmap[iter.slot >> _BITOPS_LONG_SHIFT] &= ~iter.mask;
> +}
> +
> +static inline u32 chash_iter_key32(const struct chash_iter iter)
> +{
> + BUG_ON(iter.table->key_size != 4);
> + BUG_ON((unsigned)iter.slot >= (1 << iter.table->bits));
> + return iter.table->keys32[iter.slot];
> +}
> +static inline u64 chash_iter_key64(const struct chash_iter iter)
> +{
> + BUG_ON(iter.table->key_size != 8);
> + BUG_ON((unsigned)iter.slot >= (1 << iter.table->bits));
> + return iter.table->keys64[iter.slot];
> +}
> +static inline u64 chash_iter_key(const struct chash_iter iter)
> +{
> + BUG_ON((unsigned)iter.slot >= (1 << iter.table->bits));
> + return (iter.table->key_size == 4) ?
> + iter.table->keys32[iter.slot] : iter.table->keys64[iter.slot];
> +}
> +
> +static inline u32 chash_iter_hash32(const struct chash_iter iter)
> +{
> + BUG_ON(iter.table->key_size != 4);
> + return hash_32(chash_iter_key32(iter), iter.table->bits);
> +}
> +
> +static inline u32 chash_iter_hash64(const struct chash_iter iter)
> +{
> + BUG_ON(iter.table->key_size != 8);
> + return hash_64(chash_iter_key64(iter), iter.table->bits);
> +}
> +
> +static inline u32 chash_iter_hash(const struct chash_iter iter)
> +{
> + return (iter.table->key_size == 4) ?
> + hash_32(chash_iter_key32(iter), iter.table->bits) :
> + hash_64(chash_iter_key64(iter), iter.table->bits);
> +}
> +
> +static inline void *chash_iter_value(const struct chash_iter iter)
> +{
> + BUG_ON((unsigned)iter.slot >= (1 << iter.table->bits));
> + return iter.table->values +
> + ((unsigned long)iter.slot * iter.table->value_size);
> +}
> +
> +#endif /* _LINUX_CHASH_H */
> diff --git a/drivers/gpu/drm/amd/lib/Kconfig b/drivers/gpu/drm/amd/lib/Kconfig
> new file mode 100644
> index 0000000..03ee7ad
> --- /dev/null
> +++ b/drivers/gpu/drm/amd/lib/Kconfig
> @@ -0,0 +1,27 @@
> +menu "AMD Library routines"
> +
> +#
> +# Closed hash table
> +#
> +config CHASH
> + tristate "Closed hash table"
> + help
> + Statically sized closed hash table implementation with low
> + memory and CPU overhead.
> +
> +config CHASH_STATS
> + bool "Closed hash table performance statistics"
> + depends on CHASH
> + default n
> + help
> + Enable collection of performance statistics for closed hash tables.
> +
> +config CHASH_SELFTEST
> + bool "Closed hash table self test"
> + depends on CHASH
> + default n
> + help
> + Runs a selftest during module load. Several module parameters
> + are available to modify the behaviour of the test.
> +
> +endmenu
> diff --git a/drivers/gpu/drm/amd/lib/Makefile b/drivers/gpu/drm/amd/lib/Makefile
> new file mode 100644
> index 0000000..87cd700
> --- /dev/null
> +++ b/drivers/gpu/drm/amd/lib/Makefile
> @@ -0,0 +1,11 @@
> +#
> +# Makefile for AMD library routines, which are used by AMD driver
> +# components.
> +#
> +# This is for common library routines that can be shared between AMD
> +# driver components or later moved to kernel/lib for sharing with
> +# other drivers.
> +
> +ccflags-y := -I$(src)/../include
> +
> +obj-$(CONFIG_CHASH) += chash.o
> diff --git a/drivers/gpu/drm/amd/lib/chash.c b/drivers/gpu/drm/amd/lib/chash.c
> new file mode 100644
> index 0000000..1bc4287
> --- /dev/null
> +++ b/drivers/gpu/drm/amd/lib/chash.c
> @@ -0,0 +1,622 @@
> +/*
> + * Copyright 2017 Advanced Micro Devices, Inc.
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> + * copy of this software and associated documentation files (the "Software"),
> + * to deal in the Software without restriction, including without limitation
> + * the rights to use, copy, modify, merge, publish, distribute, sublicense,
> + * and/or sell copies of the Software, and to permit persons to whom the
> + * Software is furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice shall be included in
> + * all copies or substantial portions of the Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
> + * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
> + * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
> + * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
> + * OTHER DEALINGS IN THE SOFTWARE.
> + *
> + */
> +
> +#include <linux/types.h>
> +#include <linux/hash.h>
> +#include <linux/bug.h>
> +#include <linux/slab.h>
> +#include <linux/module.h>
> +#include <linux/sched/clock.h>
> +#include <linux/chash.h>
> +
> +/**
> + * chash_table_alloc - Allocate closed hash table
> + * @table: Pointer to the table structure
> + * @bits: Table size will be 2^bits entries
> + * @key_size: Size of hash keys in bytes, 4 or 8
> + * @value_size: Size of data values in bytes, can be 0
> + */
> +int chash_table_alloc(struct chash_table *table, u8 bits, u8 key_size,
> + unsigned int value_size, gfp_t gfp_mask)
> +{
> + if (bits > 31)
> + return -EINVAL;
> +
> + if (key_size != 4 && key_size != 8)
> + return -EINVAL;
> +
> + table->data = kcalloc(__CHASH_DATA_SIZE(bits, key_size, value_size),
> + sizeof(long), gfp_mask);
> + if (!table->data)
> + return -ENOMEM;
> +
> + __CHASH_TABLE_INIT(table->table, table->data,
> + bits, key_size, value_size);
> +
> + return 0;
> +}
> +EXPORT_SYMBOL(chash_table_alloc);
> +
> +/**
> + * chash_table_free - Free closed hash table
> + * @table: Pointer to the table structure
> + */
> +void chash_table_free(struct chash_table *table)
> +{
> + kfree(table->data);
> +}
> +EXPORT_SYMBOL(chash_table_free);
> +
> +#ifdef CONFIG_CHASH_STATS
> +
> +#define DIV_FRAC(nom, denom, quot, frac, frac_digits) do { \
> + (quot) = (nom) / (denom); \
> + (frac) = ((nom) % (denom) * (frac_digits) + \
> + (denom) / 2) / (denom); \
> + } while (0)
> +
> +void __chash_table_dump_stats(struct __chash_table *table)
> +{
> + struct chash_iter iter = CHASH_ITER_INIT(table, 0);
> + u32 filled = 0, empty = 0, tombstones = 0;
> + u64 quot1, quot2;
> + u32 frac1, frac2;
> +
> + do {
> + if (chash_iter_is_valid(iter))
> + filled++;
> + else if (chash_iter_is_empty(iter))
> + empty++;
> + else
> + tombstones++;
> + CHASH_ITER_INC(iter);
> + } while (iter.slot);
> +
> + pr_debug("chash: key size %u, value size %u\n",
> + table->key_size, table->value_size);
> + pr_debug(" Slots total/filled/empty/tombstones: %u / %u / %u / %u\n",
> + 1 << table->bits, filled, empty, tombstones);
> + if (table->hits > 0) {
> + DIV_FRAC(table->hits_steps, table->hits, quot1, frac1, 1000);
> + DIV_FRAC(table->hits * 1000, table->hits_time_ns,
> + quot2, frac2, 1000);
> + } else {
> + quot1 = quot2 = 0;
> + frac1 = frac2 = 0;
> + }
> + pr_debug(" Hits (avg.cost, rate): %llu (%llu.%03u, %llu.%03u M/s)\n",
> + table->hits, quot1, frac1, quot2, frac2);
> + if (table->miss > 0) {
> + DIV_FRAC(table->miss_steps, table->miss, quot1, frac1, 1000);
> + DIV_FRAC(table->miss * 1000, table->miss_time_ns,
> + quot2, frac2, 1000);
> + } else {
> + quot1 = quot2 = 0;
> + frac1 = frac2 = 0;
> + }
> + pr_debug(" Misses (avg.cost, rate): %llu (%llu.%03u, %llu.%03u M/s)\n",
> + table->miss, quot1, frac1, quot2, frac2);
> + if (table->hits + table->miss > 0) {
> + DIV_FRAC(table->hits_steps + table->miss_steps,
> + table->hits + table->miss, quot1, frac1, 1000);
> + DIV_FRAC((table->hits + table->miss) * 1000,
> + (table->hits_time_ns + table->miss_time_ns),
> + quot2, frac2, 1000);
> + } else {
> + quot1 = quot2 = 0;
> + frac1 = frac2 = 0;
> + }
> + pr_debug(" Total (avg.cost, rate): %llu (%llu.%03u, %llu.%03u M/s)\n",
> + table->hits + table->miss, quot1, frac1, quot2, frac2);
> + if (table->relocs > 0) {
> + DIV_FRAC(table->hits + table->miss, table->relocs,
> + quot1, frac1, 1000);
> + DIV_FRAC(table->reloc_dist, table->relocs, quot2, frac2, 1000);
> + pr_debug(" Relocations (freq, avg.dist): %llu (1:%llu.%03u, %llu.%03u)\n",
> + table->relocs, quot1, frac1, quot2, frac2);
> + } else {
> + pr_debug(" No relocations\n");
> + }
> +}
> +EXPORT_SYMBOL(__chash_table_dump_stats);
> +
> +#undef DIV_FRAC
> +#endif
> +
> +#define CHASH_INC(table, a) ((a) = ((a) + 1) & (table)->size_mask)
> +#define CHASH_ADD(table, a, b) (((a) + (b)) & (table)->size_mask)
> +#define CHASH_SUB(table, a, b) (((a) - (b)) & (table)->size_mask)
> +#define CHASH_IN_RANGE(table, slot, first, last) \
> + (CHASH_SUB(table, slot, first) <= CHASH_SUB(table, last, first))
> +
> +/*#define CHASH_DEBUG Uncomment this to enable verbose debug output*/
> +#ifdef CHASH_DEBUG
> +static void chash_table_dump(struct __chash_table *table)
> +{
> + struct chash_iter iter = CHASH_ITER_INIT(table, 0);
> +
> + do {
> + if ((iter.slot & 3) == 0)
> + pr_debug("%04x: ", iter.slot);
> +
> + if (chash_iter_is_valid(iter))
> + pr_debug("[%016llx] ", chash_iter_key(iter));
> + else if (chash_iter_is_empty(iter))
> + pr_debug("[ <empty> ] ");
> + else
> + pr_debug("[ <tombstone> ] ");
> +
> + if ((iter.slot & 3) == 3)
> + pr_debug("\n");
> +
> + CHASH_ITER_INC(iter);
> + } while (iter.slot);
> +
> + if ((iter.slot & 3) != 0)
> + pr_debug("\n");
> +}
> +
> +static int chash_table_check(struct __chash_table *table)
> +{
> + u32 hash;
> + struct chash_iter iter = CHASH_ITER_INIT(table, 0);
> + struct chash_iter cur = CHASH_ITER_INIT(table, 0);
> +
> + do {
> + if (!chash_iter_is_valid(iter)) {
> + CHASH_ITER_INC(iter);
> + continue;
> + }
> +
> + hash = chash_iter_hash(iter);
> + CHASH_ITER_SET(cur, hash);
> + while (cur.slot != iter.slot) {
> + if (chash_iter_is_empty(cur)) {
> + pr_err("Path to element at %x with hash %x broken at slot %x\n",
> + iter.slot, hash, cur.slot);
> + chash_table_dump(table);
> + return -EINVAL;
> + }
> + CHASH_ITER_INC(cur);
> + }
> +
> + CHASH_ITER_INC(iter);
> + } while (iter.slot);
> +
> + return 0;
> +}
> +#endif
> +
> +static void chash_iter_relocate(struct chash_iter dst, struct chash_iter src)
> +{
> + BUG_ON(src.table == dst.table && src.slot == dst.slot);
> + BUG_ON(src.table->key_size != src.table->key_size);
> + BUG_ON(src.table->value_size != src.table->value_size);
> +
> + if (dst.table->key_size == 4)
> + dst.table->keys32[dst.slot] = src.table->keys32[src.slot];
> + else
> + dst.table->keys64[dst.slot] = src.table->keys64[src.slot];
> +
> + if (dst.table->value_size)
> + memcpy(chash_iter_value(dst), chash_iter_value(src),
> + dst.table->value_size);
> +
> + chash_iter_set_valid(dst);
> + chash_iter_set_invalid(src);
> +
> +#ifdef CONFIG_CHASH_STATS
> + if (src.table == dst.table) {
> + dst.table->relocs++;
> + dst.table->reloc_dist +=
> + CHASH_SUB(dst.table, src.slot, dst.slot);
> + }
> +#endif
> +}
> +
> +/**
> + * __chash_table_find - Helper for looking up a hash table entry
> + * @iter: Pointer to hash table iterator
> + * @key: Key of the entry to find
> + * @for_removal: set to true if the element will be removed soon
> + *
> + * Searches for an entry in the hash table with a given key. iter must
> + * be initialized by the caller to point to the home position of the
> + * hypothetical entry, i.e. it must be initialized with the hash table
> + * and the key's hash as the initial slot for the search.
> + *
> + * This function also does some local clean-up to speed up future
> + * look-ups by relocating entries to better slots and removing
> + * tombstones that are no longer needed.
> + *
> + * If @for_removal is true, the function avoids relocating the entry
> + * that is being returned.
> + *
> + * Returns 0 if the search is successful. In this case iter is updated
> + * to point to the found entry. Otherwise %-EINVAL is returned and the
> + * iter is updated to point to the first available slot for the given
> + * key. If the table is full, the slot is set to -1.
> + */
> +static int chash_table_find(struct chash_iter *iter, u64 key,
> + bool for_removal)
> +{
> +#ifdef CONFIG_CHASH_STATS
> + u64 ts1 = local_clock();
> +#endif
> + u32 hash = iter->slot;
> + struct chash_iter first_redundant = CHASH_ITER_INIT(iter->table, -1);
> + int first_avail = (for_removal ? -2 : -1);
> +
> + while (!chash_iter_is_valid(*iter) || chash_iter_key(*iter) != key) {
> + if (chash_iter_is_empty(*iter)) {
> + /* Found an empty slot, which ends the
> + * search. Clean up any preceding tombstones
> + * that are no longer needed because they lead
> + * to no-where
> + */
> + if ((int)first_redundant.slot < 0)
> + goto not_found;
> + while (first_redundant.slot != iter->slot) {
> + if (!chash_iter_is_valid(first_redundant))
> + chash_iter_set_empty(first_redundant);
> + CHASH_ITER_INC(first_redundant);
> + }
> +#ifdef CHASH_DEBUG
> + chash_table_check(iter->table);
> +#endif
> + goto not_found;
> + } else if (!chash_iter_is_valid(*iter)) {
> + /* Found a tombstone. Remember it as candidate
> + * for relocating the entry we're looking for
> + * or for adding a new entry with the given key
> + */
> + if (first_avail == -1)
> + first_avail = iter->slot;
> + /* Or mark it as the start of a series of
> + * potentially redundant tombstones
> + */
> + else if (first_redundant.slot == -1)
> + CHASH_ITER_SET(first_redundant, iter->slot);
> + } else if (first_redundant.slot >= 0) {
> + /* Found a valid, occupied slot with a
> + * preceding series of tombstones. Relocate it
> + * to a better position that no longer depends
> + * on those tombstones
> + */
> + u32 cur_hash = chash_iter_hash(*iter);
> +
> + if (!CHASH_IN_RANGE(iter->table, cur_hash,
> + first_redundant.slot + 1,
> + iter->slot)) {
> + /* This entry has a hash at or before
> + * the first tombstone we found. We
> + * can relocate it to that tombstone
> + * and advance to the next tombstone
> + */
> + chash_iter_relocate(first_redundant, *iter);
> + do {
> + CHASH_ITER_INC(first_redundant);
> + } while (chash_iter_is_valid(first_redundant));
> + } else if (cur_hash != iter->slot) {
> + /* Relocate entry to its home position
> + * or as close as possible so it no
> + * longer depends on any preceding
> + * tombstones
> + */
> + struct chash_iter new_iter =
> + CHASH_ITER_INIT(iter->table, cur_hash);
> +
> + while (new_iter.slot != iter->slot &&
> + chash_iter_is_valid(new_iter))
> + CHASH_ITER_INC(new_iter);
> +
> + if (new_iter.slot != iter->slot)
> + chash_iter_relocate(new_iter, *iter);
> + }
> + }
> +
> + CHASH_ITER_INC(*iter);
> + if (iter->slot == hash) {
> + iter->slot = -1;
> + goto not_found;
> + }
> + }
> +
> +#ifdef CONFIG_CHASH_STATS
> + iter->table->hits++;
> + iter->table->hits_steps += CHASH_SUB(iter->table, iter->slot, hash) + 1;
> +#endif
> +
> + if (first_avail >= 0) {
> + CHASH_ITER_SET(first_redundant, first_avail);
> + chash_iter_relocate(first_redundant, *iter);
> + iter->slot = first_redundant.slot;
> + iter->mask = first_redundant.mask;
> + }
> +
> +#ifdef CONFIG_CHASH_STATS
> + iter->table->hits_time_ns += local_clock() - ts1;
> +#endif
> +
> + return 0;
> +
> +not_found:
> +#ifdef CONFIG_CHASH_STATS
> + iter->table->miss++;
> + iter->table->miss_steps += (iter->slot < 0) ?
> + (1 << iter->table->bits) :
> + CHASH_SUB(iter->table, iter->slot, hash) + 1;
> +#endif
> +
> + if (first_avail >= 0)
> + CHASH_ITER_SET(*iter, first_avail);
> +
> +#ifdef CONFIG_CHASH_STATS
> + iter->table->miss_time_ns += local_clock() - ts1;
> +#endif
> +
> + return -EINVAL;
> +}
> +
> +int __chash_table_copy_in(struct __chash_table *table, u64 key,
> + const void *value)
> +{
> + u32 hash = (table->key_size == 4) ?
> + hash_32(key, table->bits) : hash_64(key, table->bits);
> + struct chash_iter iter = CHASH_ITER_INIT(table, hash);
> + int r = chash_table_find(&iter, key, false);
> +
> + /* Found an existing entry */
> + if (!r) {
> + if (value && table->value_size)
> + memcpy(chash_iter_value(iter), value,
> + table->value_size);
> + return 1;
> + }
> +
> + /* Is there a place to add a new entry? */
> + if (iter.slot < 0) {
> + pr_err("Hash table overflow\n");
> + return -ENOMEM;
> + }
> +
> + chash_iter_set_valid(iter);
> +
> + if (table->key_size == 4)
> + table->keys32[iter.slot] = key;
> + else
> + table->keys64[iter.slot] = key;
> + if (value && table->value_size)
> + memcpy(chash_iter_value(iter), value, table->value_size);
> +
> + return 0;
> +}
> +EXPORT_SYMBOL(__chash_table_copy_in);
> +
> +int __chash_table_copy_out(struct __chash_table *table, u64 key,
> + void *value, bool remove)
> +{
> + u32 hash = (table->key_size == 4) ?
> + hash_32(key, table->bits) : hash_64(key, table->bits);
> + struct chash_iter iter = CHASH_ITER_INIT(table, hash);
> + int r = chash_table_find(&iter, key, remove);
> +
> + if (r < 0)
> + return r;
> +
> + if (value && table->value_size)
> + memcpy(value, chash_iter_value(iter), table->value_size);
> +
> + if (remove)
> + chash_iter_set_invalid(iter);
> +
> + return iter.slot;
> +}
> +EXPORT_SYMBOL(__chash_table_copy_out);
> +
> +#ifdef CONFIG_CHASH_SELFTEST
> +/**
> + * chash_self_test - Run a self-test of the hash table implementation
> + * @bits: Table size will be 2^bits entries
> + * @key_size: Size of hash keys in bytes, 4 or 8
> + * @min_fill: Minimum fill level during the test
> + * @max_fill: Maximum fill level during the test
> + * @iterations: Number of test iterations
> + *
> + * The test adds and removes entries from a hash table, cycling the
> + * fill level between min_fill and max_fill entries. Also tests lookup
> + * and value retrieval.
> + */
> +static int __init chash_self_test(u8 bits, u8 key_size,
> + int min_fill, int max_fill,
> + u64 iterations)
> +{
> + struct chash_table table;
> + int ret;
> + u64 add_count, rmv_count;
> + u64 value;
> +
> + if (key_size == 4 && iterations > 0xffffffff)
> + return -EINVAL;
> + if (min_fill >= max_fill)
> + return -EINVAL;
> +
> + ret = chash_table_alloc(&table, bits, key_size, sizeof(u64),
> + GFP_KERNEL);
> + if (ret) {
> + pr_err("chash_table_alloc failed: %d\n", ret);
> + return ret;
> + }
> +
> + for (add_count = 0, rmv_count = 0; add_count < iterations;
> + add_count++) {
> + /* When we hit the max_fill level, remove entries down
> + * to min_fill
> + */
> + if (add_count - rmv_count == max_fill) {
> + u64 find_count = rmv_count;
> +
> + /* First try to find all entries that we're
> + * about to remove, confirm their value, test
> + * writing them back a second time.
> + */
> + for (; add_count - find_count > min_fill;
> + find_count++) {
> + ret = chash_table_copy_out(&table, find_count,
> + &value);
> + if (ret < 0) {
> + pr_err("chash_table_copy_out failed: %d\n",
> + ret);
> + goto out;
> + }
> + if (value != ~find_count) {
> + pr_err("Wrong value retrieved for key 0x%llx, expected 0x%llx got 0x%llx\n",
> + find_count, ~find_count, value);
> +#ifdef CHASH_DEBUG
> + chash_table_dump(&table.table);
> +#endif
> + ret = -EFAULT;
> + goto out;
> + }
> + ret = chash_table_copy_in(&table, find_count,
> + &value);
> + if (ret != 1) {
> + pr_err("copy_in second time returned %d, expected 1\n",
> + ret);
> + ret = -EFAULT;
> + goto out;
> + }
> + }
> + /* Remove them until we hit min_fill level */
> + for (; add_count - rmv_count > min_fill; rmv_count++) {
> + ret = chash_table_remove(&table, rmv_count,
> + NULL);
> + if (ret < 0) {
> + pr_err("chash_table_remove failed: %d\n",
> + ret);
> + goto out;
> + }
> + }
> + }
> +
> + /* Add a new value */
> + value = ~add_count;
> + ret = chash_table_copy_in(&table, add_count, &value);
> + if (ret != 0) {
> + pr_err("copy_in first time returned %d, expected 0\n",
> + ret);
> + ret = -EFAULT;
> + goto out;
> + }
> + }
> +
> + chash_table_dump_stats(&table);
> + chash_table_reset_stats(&table);
> +
> +out:
> + chash_table_free(&table);
> + return ret;
> +}
> +
> +static unsigned int chash_test_bits = 10;
> +MODULE_PARM_DESC(test_bits,
> + "Selftest number of hash bits ([4..20], default=10)");
> +module_param_named(test_bits, chash_test_bits, uint, 0444);
> +
> +static unsigned int chash_test_keysize = 8;
> +MODULE_PARM_DESC(test_keysize, "Selftest keysize (4 or 8, default=8)");
> +module_param_named(test_keysize, chash_test_keysize, uint, 0444);
> +
> +static unsigned int chash_test_minfill;
> +MODULE_PARM_DESC(test_minfill, "Selftest minimum #entries (default=50%)");
> +module_param_named(test_minfill, chash_test_minfill, uint, 0444);
> +
> +static unsigned int chash_test_maxfill;
> +MODULE_PARM_DESC(test_maxfill, "Selftest maximum #entries (default=80%)");
> +module_param_named(test_maxfill, chash_test_maxfill, uint, 0444);
> +
> +static unsigned long chash_test_iters;
> +MODULE_PARM_DESC(test_iters, "Selftest iterations (default=1000 x #entries)");
> +module_param_named(test_iters, chash_test_iters, ulong, 0444);
> +
> +static int __init chash_init(void)
> +{
> + int ret;
> + u64 ts1_ns, ts_delta_us;
> +
> + /* Skip self test on user errors */
> + if (chash_test_bits < 4 || chash_test_bits > 20) {
> + pr_err("chash: test_bits out of range [4..20].\n");
> + return 0;
> + }
> + if (chash_test_keysize != 4 && chash_test_keysize != 8) {
> + pr_err("chash: test_keysize invalid. Must be 4 or 8.\n");
> + return 0;
> + }
> +
> + if (!chash_test_minfill)
> + chash_test_minfill = (1 << chash_test_bits) / 2;
> + if (!chash_test_maxfill)
> + chash_test_maxfill = (1 << chash_test_bits) * 4 / 5;
> + if (!chash_test_iters)
> + chash_test_iters = (1 << chash_test_bits) * 1000;
> +
> + if (chash_test_minfill >= (1 << chash_test_bits)) {
> + pr_err("chash: test_minfill too big. Must be < table size.\n");
> + return 0;
> + }
> + if (chash_test_maxfill >= (1 << chash_test_bits)) {
> + pr_err("chash: test_maxfill too big. Must be < table size.\n");
> + return 0;
> + }
> + if (chash_test_minfill >= chash_test_maxfill) {
> + pr_err("chash: test_minfill must be < test_maxfill.\n");
> + return 0;
> + }
> + if (chash_test_keysize == 4 && chash_test_iters > 0xffffffff) {
> + pr_err("chash: test_iters must be < 4G for 4 byte keys.\n");
> + return 0;
> + }
> +
> + ts1_ns = local_clock();
> + ret = chash_self_test(chash_test_bits, chash_test_keysize,
> + chash_test_minfill, chash_test_maxfill,
> + chash_test_iters);
> + if (!ret) {
> + ts_delta_us = (local_clock() - ts1_ns) / 1000;
> + pr_info("chash: self test took %llu us, %llu iterations/s\n",
> + ts_delta_us,
> + (u64)chash_test_iters * 1000000 / ts_delta_us);
> + } else {
> + pr_err("chash: self test failed: %d\n", ret);
> + }
> +
> + return ret;
> +}
> +
> +module_init(chash_init);
> +
> +#endif /* CONFIG_CHASH_SELFTEST */
> +
> +MODULE_DESCRIPTION("Closed hash table");
> +MODULE_LICENSE("GPL and additional rights");
> --
> 2.7.4
>
> _______________________________________________
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> amd-gfx at lists.freedesktop.org
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