Commit ceb029cd authored by Vladimir Sementsov-Ogievskiy's avatar Vladimir Sementsov-Ogievskiy Committed by Kevin Wolf
Browse files

qcow2: add compress threads 



Do data compression in separate threads. This significantly improve
performance for qemu-img convert with -W (allow async writes) and -c
(compressed) options.

Signed-off-by: default avatarVladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent 2714f13d

block/qcow2.c

+61 −1
Original line number Diff line number Diff line
@@ -44,6 +44,7 @@ 
#include "qapi/qobject-input-visitor.h"

#include "qapi/qapi-visit-block-core.h"

#include "crypto.h"

#include "block/thread-pool.h"



/*

  Differences with QCOW:
@@ -1544,6 +1545,9 @@ static int coroutine_fn qcow2_do_open(BlockDriverState *bs, QDict *options, 
        qcow2_check_refcounts(bs, &result, 0);

    }

#endif



    qemu_co_queue_init(&s->compress_wait_queue);



    return ret;



 fail:
@@ -3695,6 +3699,62 @@ static ssize_t qcow2_compress(void *dest, const void *src, size_t size) 
    return ret;

}



#define MAX_COMPRESS_THREADS 4



typedef struct Qcow2CompressData {

    void *dest;

    const void *src;

    size_t size;

    ssize_t ret;

} Qcow2CompressData;



static int qcow2_compress_pool_func(void *opaque)

{

    Qcow2CompressData *data = opaque;



    data->ret = qcow2_compress(data->dest, data->src, data->size);



    return 0;

}



static void qcow2_compress_complete(void *opaque, int ret)

{

    qemu_coroutine_enter(opaque);

}



/* See qcow2_compress definition for parameters description */

static ssize_t qcow2_co_compress(BlockDriverState *bs,

                                 void *dest, const void *src, size_t size)

{

    BDRVQcow2State *s = bs->opaque;

    BlockAIOCB *acb;

    ThreadPool *pool = aio_get_thread_pool(bdrv_get_aio_context(bs));

    Qcow2CompressData arg = {

        .dest = dest,

        .src = src,

        .size = size,

    };



    while (s->nb_compress_threads >= MAX_COMPRESS_THREADS) {

        qemu_co_queue_wait(&s->compress_wait_queue, NULL);

    }



    s->nb_compress_threads++;

    acb = thread_pool_submit_aio(pool, qcow2_compress_pool_func, &arg,

                                 qcow2_compress_complete,

                                 qemu_coroutine_self());



    if (!acb) {

        s->nb_compress_threads--;

        return -EINVAL;

    }

    qemu_coroutine_yield();

    s->nb_compress_threads--;

    qemu_co_queue_next(&s->compress_wait_queue);



    return arg.ret;

}



/* XXX: put compressed sectors first, then all the cluster aligned

   tables to avoid losing bytes in alignment */

static coroutine_fn int
@@ -3739,7 +3799,7 @@ qcow2_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset, 


    out_buf = g_malloc(s->cluster_size);



    out_len = qcow2_compress(out_buf, buf, s->cluster_size);

    out_len = qcow2_co_compress(bs, out_buf, buf, s->cluster_size);

    if (out_len == -2) {

        ret = -EINVAL;

        goto fail;

block/qcow2.h

+3 −0
Original line number Diff line number Diff line
@@ -326,6 +326,9 @@ typedef struct BDRVQcow2State { 
     * override) */

    char *image_backing_file;

    char *image_backing_format;



    CoQueue compress_wait_queue;

    int nb_compress_threads;

} BDRVQcow2State;



typedef struct Qcow2COWRegion {