SIMD implementation of vdev_raidz generate and reconstruct routines

[mirror_zfs.git] / module / zfs / vdev_raidz_math.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright (C) 2016 Gvozden Nešković. All rights reserved.
 */

#include <sys/zfs_context.h>
#include <sys/types.h>
#include <sys/zio.h>
#include <sys/debug.h>
#include <sys/zfs_debug.h>

#include <sys/vdev_raidz.h>
#include <sys/vdev_raidz_impl.h>

extern const raidz_impl_ops_t vdev_raidz_scalar_impl;
extern const raidz_impl_ops_t vdev_raidz_sse_impl;
extern const raidz_impl_ops_t vdev_raidz_avx2_impl;

/* All compiled in implementations */
const raidz_impl_ops_t *raidz_all_maths[] = {
        &vdev_raidz_scalar_impl,
#if defined(__x86_64) && defined(HAVE_SSSE3)    /* only x86_64 for now */
        &vdev_raidz_sse_impl,
#endif
#if defined(__x86_64) && defined(HAVE_AVX2)     /* only x86_64 for now */
        &vdev_raidz_avx2_impl
#endif
};

/* Indicate that benchmark has been completed */
static boolean_t raidz_math_initialized = B_FALSE;

/* Select raidz implementation */
static enum vdev_raidz_impl_sel {
        IMPL_FASTEST    = -1,
        IMPL_ORIGINAL   = -2,
        IMPL_CYCLE      = -3,
        IMPL_SCALAR     =  0,
} zfs_vdev_raidz_impl = IMPL_SCALAR;

/* selected implementation and its lock */
static krwlock_t vdev_raidz_impl_lock;
static raidz_impl_ops_t *vdev_raidz_used_impl =
        (raidz_impl_ops_t *) &vdev_raidz_scalar_impl;
static boolean_t vdev_raidz_impl_user_set = B_FALSE;

/* RAIDZ op that contain the fastest routines */
static raidz_impl_ops_t vdev_raidz_fastest_impl = {
        .name = "fastest"
};

/* Hold all supported implementations */
size_t raidz_supp_impl_cnt = 1;
raidz_impl_ops_t *raidz_supp_impl[ARRAY_SIZE(raidz_all_maths) + 1] = {
        (raidz_impl_ops_t *) &vdev_raidz_scalar_impl, /* scalar is supported */
        NULL
};

/*
 * kstats values for supported impl & original methods
 * Values represent per disk throughput of 8 disk+parity raidz vdev (Bps)
 */
static raidz_impl_kstat_t raidz_impl_kstats[ARRAY_SIZE(raidz_all_maths) + 1];

/* kstat for benchmarked implementations */
static kstat_t *raidz_math_kstat = NULL;

/*
 * Selects the raidz operation for raidz_map
 * If rm_ops is set to NULL original raidz implementation will be used
 */
void
vdev_raidz_math_get_ops(raidz_map_t *rm)
{
        rw_enter(&vdev_raidz_impl_lock, RW_READER);

        rm->rm_ops = vdev_raidz_used_impl;

#if !defined(_KERNEL)
        if (zfs_vdev_raidz_impl == IMPL_CYCLE) {
                static size_t cycle_impl_idx = 0;
                size_t idx;
                /*
                 * Cycle through all supported new implementations, and
                 * when idx == raidz_supp_impl_cnt, use the original
                 */
                idx = (++cycle_impl_idx) % (raidz_supp_impl_cnt + 1);
                rm->rm_ops = raidz_supp_impl[idx];
        }
#endif

        rw_exit(&vdev_raidz_impl_lock);
}

/*
 * Select parity generation method for raidz_map
 */
void
vdev_raidz_math_generate(raidz_map_t *rm)
{
        raidz_gen_f gen_parity = NULL;

        switch (raidz_parity(rm)) {
                case 1:
                        gen_parity = rm->rm_ops->gen[RAIDZ_GEN_P];
                        break;
                case 2:
                        gen_parity = rm->rm_ops->gen[RAIDZ_GEN_PQ];
                        break;
                case 3:
                        gen_parity = rm->rm_ops->gen[RAIDZ_GEN_PQR];
                        break;
                default:
                        gen_parity = NULL;
                        cmn_err(CE_PANIC, "invalid RAID-Z configuration %d",
                                raidz_parity(rm));
                        break;
        }

        ASSERT(gen_parity != NULL);

        gen_parity(rm);
}

static raidz_rec_f
_reconstruct_fun_raidz1(raidz_map_t *rm, const int *parity_valid,
        const int nbaddata)
{
        if (nbaddata == 1 && parity_valid[CODE_P]) {
                return (rm->rm_ops->rec[RAIDZ_REC_P]);
        }
        return ((raidz_rec_f) NULL);
}

static raidz_rec_f
_reconstruct_fun_raidz2(raidz_map_t *rm, const int *parity_valid,
        const int nbaddata)
{
        if (nbaddata == 1) {
                if (parity_valid[CODE_P]) {
                        return (rm->rm_ops->rec[RAIDZ_REC_P]);
                } else if (parity_valid[CODE_Q]) {
                        return (rm->rm_ops->rec[RAIDZ_REC_Q]);
                }
        } else if (nbaddata == 2 &&
                parity_valid[CODE_P] && parity_valid[CODE_Q]) {
                return (rm->rm_ops->rec[RAIDZ_REC_PQ]);
        }
        return ((raidz_rec_f) NULL);
}

static raidz_rec_f
_reconstruct_fun_raidz3(raidz_map_t *rm, const int *parity_valid,
        const int nbaddata)
{
        if (nbaddata == 1) {
                if (parity_valid[CODE_P]) {
                        return (rm->rm_ops->rec[RAIDZ_REC_P]);
                } else if (parity_valid[CODE_Q]) {
                        return (rm->rm_ops->rec[RAIDZ_REC_Q]);
                } else if (parity_valid[CODE_R]) {
                        return (rm->rm_ops->rec[RAIDZ_REC_R]);
                }
        } else if (nbaddata == 2) {
                if (parity_valid[CODE_P] && parity_valid[CODE_Q]) {
                        return (rm->rm_ops->rec[RAIDZ_REC_PQ]);
                } else if (parity_valid[CODE_P] && parity_valid[CODE_R]) {
                        return (rm->rm_ops->rec[RAIDZ_REC_PR]);
                } else if (parity_valid[CODE_Q] && parity_valid[CODE_R]) {
                        return (rm->rm_ops->rec[RAIDZ_REC_QR]);
                }
        } else if (nbaddata == 3 &&
                parity_valid[CODE_P] && parity_valid[CODE_Q] &&
                parity_valid[CODE_R]) {
                return (rm->rm_ops->rec[RAIDZ_REC_PQR]);
        }
        return ((raidz_rec_f) NULL);
}

/*
 * Select data reconstruction method for raidz_map
 * @parity_valid - Parity validity flag
 * @dt           - Failed data index array
 * @nbaddata     - Number of failed data columns
 */
int
vdev_raidz_math_reconstruct(raidz_map_t *rm, const int *parity_valid,
        const int *dt, const int nbaddata)
{
        raidz_rec_f rec_data = NULL;

        switch (raidz_parity(rm)) {
                case 1:
                        rec_data = _reconstruct_fun_raidz1(rm, parity_valid,
                            nbaddata);
                        break;
                case 2:
                        rec_data = _reconstruct_fun_raidz2(rm, parity_valid,
                            nbaddata);
                        break;
                case 3:
                        rec_data = _reconstruct_fun_raidz3(rm, parity_valid,
                            nbaddata);
                        break;
                default:
                        cmn_err(CE_PANIC, "invalid RAID-Z configuration %d",
                            raidz_parity(rm));
                        break;
        }

        ASSERT(rec_data != NULL);

        return (rec_data(rm, dt));
}

const char *raidz_gen_name[] = {
        "gen_p", "gen_pq", "gen_pqr"
};
const char *raidz_rec_name[] = {
        "rec_p", "rec_q", "rec_r",
        "rec_pq", "rec_pr", "rec_qr", "rec_pqr"
};

static void
init_raidz_kstat(raidz_impl_kstat_t *rs, const char *name)
{
        int i;
        const size_t impl_name_len = strnlen(name, KSTAT_STRLEN);
        const size_t op_name_max = (KSTAT_STRLEN - 2) > impl_name_len ?
                KSTAT_STRLEN - impl_name_len - 2 : 0;

        for (i = 0; i < RAIDZ_GEN_NUM; i++) {
                strncpy(rs->gen[i].name, name, impl_name_len);
                strncpy(rs->gen[i].name + impl_name_len, "_", 1);
                strncpy(rs->gen[i].name + impl_name_len + 1,
                        raidz_gen_name[i], op_name_max);

                rs->gen[i].data_type = KSTAT_DATA_UINT64;
                rs->gen[i].value.ui64  = 0;
        }

        for (i = 0; i < RAIDZ_REC_NUM; i++) {
                strncpy(rs->rec[i].name, name, impl_name_len);
                strncpy(rs->rec[i].name + impl_name_len, "_", 1);
                strncpy(rs->rec[i].name + impl_name_len + 1,
                        raidz_rec_name[i], op_name_max);

                rs->rec[i].data_type = KSTAT_DATA_UINT64;
                rs->rec[i].value.ui64  = 0;
        }
}

#define BENCH_D_COLS    (8ULL)
#define BENCH_COLS      (BENCH_D_COLS + PARITY_PQR)
#define BENCH_ZIO_SIZE  (2ULL << 17)                    /* 128 kiB */
#define BENCH_NS        MSEC2NSEC(25)                   /* 25ms */

typedef void (*benchmark_fn)(raidz_map_t *rm, const int fn);

static void
benchmark_gen_impl(raidz_map_t *rm, const int fn)
{
        (void) fn;
        vdev_raidz_generate_parity(rm);
}

static void
benchmark_rec_impl(raidz_map_t *rm, const int fn)
{
        static const int rec_tgt[7][3] = {
                {1, 2, 3},      /* rec_p:   bad QR & D[0]       */
                {0, 2, 3},      /* rec_q:   bad PR & D[0]       */
                {0, 1, 3},      /* rec_r:   bad PQ & D[0]       */
                {2, 3, 4},      /* rec_pq:  bad R  & D[0][1]    */
                {1, 3, 4},      /* rec_pr:  bad Q  & D[0][1]    */
                {0, 3, 4},      /* rec_qr:  bad P  & D[0][1]    */
                {3, 4, 5}       /* rec_pqr: bad    & D[0][1][2] */
        };

        vdev_raidz_reconstruct(rm, rec_tgt[fn], 3);
}

/*
 * Benchmarking of all supported implementations (raidz_supp_impl_cnt)
 * is performed by setting the rm_ops pointer and calling the top level
 * generate/reconstruct methods of bench_rm.
 */
static void
benchmark_raidz_impl(raidz_map_t *bench_rm, const int fn, benchmark_fn bench_fn)
{
        uint64_t run_cnt, speed, best_speed = 0;
        hrtime_t t_start, t_diff;
        raidz_impl_ops_t *curr_impl;
        int impl, i;

        /*
         * Use the sentinel (NULL) from the end of raidz_supp_impl_cnt
         * to run "original" implementation (bench_rm->rm_ops = NULL)
         */
        for (impl = 0; impl <= raidz_supp_impl_cnt; impl++) {
                /* set an implementation to benchmark */
                curr_impl = raidz_supp_impl[impl];
                bench_rm->rm_ops = curr_impl;

                run_cnt = 0;
                t_start = gethrtime();

                do {
                        for (i = 0; i < 25; i++, run_cnt++)
                                bench_fn(bench_rm, fn);

                        t_diff = gethrtime() - t_start;
                } while (t_diff < BENCH_NS);

                speed = run_cnt * BENCH_ZIO_SIZE * NANOSEC;
                speed /= (t_diff * BENCH_COLS);

                if (bench_fn == benchmark_gen_impl)
                        raidz_impl_kstats[impl].gen[fn].value.ui64 = speed;
                else
                        raidz_impl_kstats[impl].rec[fn].value.ui64 = speed;

                /* if curr_impl==NULL the original impl is benchmarked */
                if (curr_impl != NULL && speed > best_speed) {
                        best_speed = speed;

                        if (bench_fn == benchmark_gen_impl)
                                vdev_raidz_fastest_impl.gen[fn] =
                                    curr_impl->gen[fn];
                        else
                                vdev_raidz_fastest_impl.rec[fn] =
                                    curr_impl->rec[fn];
                }
        }
}

void
vdev_raidz_math_init(void)
{
        raidz_impl_ops_t *curr_impl;
        zio_t *bench_zio = NULL;
        raidz_map_t *bench_rm = NULL;
        uint64_t bench_parity;
        int i, c, fn;

        /* init & vdev_raidz_impl_lock */
        rw_init(&vdev_raidz_impl_lock, NULL, RW_DEFAULT, NULL);

        /* move supported impl into raidz_supp_impl */
        for (i = 0, c = 0; i < ARRAY_SIZE(raidz_all_maths); i++) {
                curr_impl = (raidz_impl_ops_t *) raidz_all_maths[i];

                /* initialize impl */
                if (curr_impl->init)
                        curr_impl->init();

                if (curr_impl->is_supported()) {
                        /* init kstat */
                        init_raidz_kstat(&raidz_impl_kstats[c],
                            curr_impl->name);
                        raidz_supp_impl[c++] = (raidz_impl_ops_t *) curr_impl;
                }
        }
        raidz_supp_impl_cnt = c;        /* number of supported impl */
        raidz_supp_impl[c] = NULL;      /* sentinel */

        /* init kstat for original routines */
        init_raidz_kstat(&(raidz_impl_kstats[raidz_supp_impl_cnt]), "original");

#if !defined(_KERNEL)
        /*
         * Skip benchmarking and use last implementation as fastest
         */
        memcpy(&vdev_raidz_fastest_impl, raidz_supp_impl[raidz_supp_impl_cnt-1],
            sizeof (vdev_raidz_fastest_impl));

        vdev_raidz_fastest_impl.name = "fastest";

        raidz_math_initialized = B_TRUE;

        /* Use 'cycle' math selection method for userspace */
        VERIFY0(vdev_raidz_impl_set("cycle"));
        return;
#endif

        /* Fake an zio and run the benchmark on it */
        bench_zio = kmem_zalloc(sizeof (zio_t), KM_SLEEP);
        bench_zio->io_offset = 0;
        bench_zio->io_size = BENCH_ZIO_SIZE; /* only data columns */
        bench_zio->io_data = zio_data_buf_alloc(BENCH_ZIO_SIZE);
        VERIFY(bench_zio->io_data);

        /* Benchmark parity generation methods */
        for (fn = 0; fn < RAIDZ_GEN_NUM; fn++) {
                bench_parity = fn + 1;
                /* New raidz_map is needed for each generate_p/q/r */
                bench_rm = vdev_raidz_map_alloc(bench_zio, 9,
                    BENCH_D_COLS + bench_parity, bench_parity);

                benchmark_raidz_impl(bench_rm, fn, benchmark_gen_impl);

                vdev_raidz_map_free(bench_rm);
        }

        /* Benchmark data reconstruction methods */
        bench_rm = vdev_raidz_map_alloc(bench_zio, 9, BENCH_COLS, PARITY_PQR);

        for (fn = 0; fn < RAIDZ_REC_NUM; fn++)
                benchmark_raidz_impl(bench_rm, fn, benchmark_rec_impl);

        vdev_raidz_map_free(bench_rm);

        /* cleanup the bench zio */
        zio_data_buf_free(bench_zio->io_data, BENCH_ZIO_SIZE);
        kmem_free(bench_zio, sizeof (zio_t));

        /* install kstats for all impl */
        raidz_math_kstat = kstat_create("zfs", 0, "vdev_raidz_bench",
                "misc", KSTAT_TYPE_NAMED,
                sizeof (raidz_impl_kstat_t) / sizeof (kstat_named_t) *
                (raidz_supp_impl_cnt + 1), KSTAT_FLAG_VIRTUAL);

        if (raidz_math_kstat != NULL) {
                raidz_math_kstat->ks_data = raidz_impl_kstats;
                kstat_install(raidz_math_kstat);
        }

        /* Finish initialization */
        raidz_math_initialized = B_TRUE;
        if (!vdev_raidz_impl_user_set)
                VERIFY0(vdev_raidz_impl_set("fastest"));
}

void
vdev_raidz_math_fini(void)
{
        raidz_impl_ops_t const *curr_impl;
        int i;

        if (raidz_math_kstat != NULL) {
                kstat_delete(raidz_math_kstat);
                raidz_math_kstat = NULL;
        }

        rw_destroy(&vdev_raidz_impl_lock);

        /* fini impl */
        for (i = 0; i < ARRAY_SIZE(raidz_all_maths); i++) {
                curr_impl = raidz_all_maths[i];

                if (curr_impl->fini)
                        curr_impl->fini();
        }
}

static const
struct {
        char *name;
        raidz_impl_ops_t *impl;
        enum vdev_raidz_impl_sel sel;
} math_impl_opts[] = {
                { "fastest",  &vdev_raidz_fastest_impl, IMPL_FASTEST },
                { "original", NULL, IMPL_ORIGINAL },
#if !defined(_KERNEL)
                { "cycle",    NULL, IMPL_CYCLE },
#endif
};

/*
 * Function sets desired raidz implementation.
 * If called after module_init(), vdev_raidz_impl_lock must be held for writing.
 *
 * @val         Name of raidz implementation to use
 * @param       Unused.
 */
static int
zfs_vdev_raidz_impl_set(const char *val, struct kernel_param *kp)
{
        size_t i;

        /* Check mandatory options */
        for (i = 0; i < ARRAY_SIZE(math_impl_opts); i++) {
                if (strcmp(val, math_impl_opts[i].name) == 0) {
                        zfs_vdev_raidz_impl = math_impl_opts[i].sel;
                        vdev_raidz_used_impl = math_impl_opts[i].impl;
                        vdev_raidz_impl_user_set = B_TRUE;
                        return (0);
                }
        }

        /* check all supported implementations */
        for (i = 0; i < raidz_supp_impl_cnt; i++) {
                if (strcmp(val, raidz_supp_impl[i]->name) == 0) {
                        zfs_vdev_raidz_impl = i;
                        vdev_raidz_used_impl = raidz_supp_impl[i];
                        vdev_raidz_impl_user_set = B_TRUE;
                        return (0);
                }
        }

        return (-EINVAL);
}

int
vdev_raidz_impl_set(const char *val)
{
        int err;

        ASSERT(raidz_math_initialized);

        rw_enter(&vdev_raidz_impl_lock, RW_WRITER);
        err = zfs_vdev_raidz_impl_set(val, NULL);
        rw_exit(&vdev_raidz_impl_lock);
        return (err);
}

#if defined(_KERNEL) && defined(HAVE_SPL)
static int
zfs_vdev_raidz_impl_get(char *buffer, struct kernel_param *kp)
{
        int i, cnt = 0;
        char *fmt;

        ASSERT(raidz_math_initialized);

        rw_enter(&vdev_raidz_impl_lock, RW_READER);

        /* list mandatory options */
        for (i = 0; i < ARRAY_SIZE(math_impl_opts); i++) {
                if (math_impl_opts[i].sel == zfs_vdev_raidz_impl)
                        fmt = "[%s] ";
                else
                        fmt = "%s ";

                cnt += sprintf(buffer + cnt, fmt, math_impl_opts[i].name);
        }

        /* list all supported implementations */
        for (i = 0; i < raidz_supp_impl_cnt; i++) {
                fmt = (i == zfs_vdev_raidz_impl) ? "[%s] " : "%s ";
                cnt += sprintf(buffer + cnt, fmt, raidz_supp_impl[i]->name);
        }

        rw_exit(&vdev_raidz_impl_lock);

        return (cnt);
}

module_param_call(zfs_vdev_raidz_impl, zfs_vdev_raidz_impl_set,
        zfs_vdev_raidz_impl_get, NULL, 0644);
MODULE_PARM_DESC(zfs_vdev_raidz_impl, "Select raidz implementation.");
#endif