* David Edmondson (d...@dme.org) wrote:
> On Monday, 2020-08-24 at 17:14:34 +08, Chuan Zheng wrote:
>
> > Record hash results for each sampled page, crc32 is taken to calculate
> > hash results for each sampled 4K-page.
> >
> > Signed-off-by: Chuan Zheng <zhengch...@huawei.com>
> > Signed-off-by: YanYing Zhuang <ann.zhuangyany...@huawei.com>
> > ---
> > migration/dirtyrate.c | 136
> > ++++++++++++++++++++++++++++++++++++++++++++++++++
> > migration/dirtyrate.h | 15 ++++++
> > 2 files changed, 151 insertions(+)
> >
> > diff --git a/migration/dirtyrate.c b/migration/dirtyrate.c
> > index f6a94d8..66de426 100644
> > --- a/migration/dirtyrate.c
> > +++ b/migration/dirtyrate.c
> > @@ -10,6 +10,7 @@
> > * See the COPYING file in the top-level directory.
> > */
> >
> > +#include <zlib.h>
> > #include "qemu/osdep.h"
> > #include "qapi/error.h"
> > #include "crypto/hash.h"
> > @@ -66,6 +67,141 @@ static void update_dirtyrate(uint64_t msec)
> > DirtyStat.dirty_rate = dirtyrate;
> > }
> >
> > +/*
> > + * get hash result for the sampled memory with length of 4K byte in
> > ramblock,
> > + * which starts from ramblock base address.
> > + */
> > +static uint32_t get_ramblock_vfn_hash(struct RamblockDirtyInfo *info,
> > + uint64_t vfn)
> > +{
> > + struct iovec iov_array;
>
> There's no need for an iovec now that crc32() is being used.
>
> > + uint32_t crc;
> > +
> > + iov_array.iov_base = info->ramblock_addr +
> > + vfn * DIRTYRATE_SAMPLE_PAGE_SIZE;
> > + iov_array.iov_len = DIRTYRATE_SAMPLE_PAGE_SIZE;
> > +
> > + crc = crc32(0, iov_array.iov_base, iov_array.iov_len);
> > +
> > + return crc;
> > +}
> > +
> > +static int save_ramblock_hash(struct RamblockDirtyInfo *info)
> > +{
> > + unsigned int sample_pages_count;
> > + int i;
> > + int ret = -1;
>
> There's no need to initialise "ret".
>
> > + GRand *rand = g_rand_new();
>
> Calling g_rand_new() when the result may not be used (because of the
> various conditions immediately below) seems as though it might waste
> entropy. Could this be pushed down just above the loop? It would even
> get rid of the gotos ;-)
>
> > + sample_pages_count = info->sample_pages_count;
> > +
> > + /* ramblock size less than one page, return success to skip this
> > ramblock */
> > + if (unlikely(info->ramblock_pages == 0 || sample_pages_count == 0)) {
> > + ret = 0;
> > + goto out;
> > + }
> > +
> > + info->hash_result = g_try_malloc0_n(sample_pages_count,
> > + sizeof(uint32_t));
> > + if (!info->hash_result) {
> > + ret = -1;
> > + goto out;
> > + }
> > +
> > + info->sample_page_vfn = g_try_malloc0_n(sample_pages_count,
> > + sizeof(uint64_t));
> > + if (!info->sample_page_vfn) {
> > + g_free(info->hash_result);
> > + ret = -1;
> > + goto out;
> > + }
> > +
> > + for (i = 0; i < sample_pages_count; i++) {
> > + info->sample_page_vfn[i] = g_rand_int_range(rand, 0,
> > + info->ramblock_pages -
> > 1);
> > + info->hash_result[i] = get_ramblock_vfn_hash(info,
> > +
> > info->sample_page_vfn[i]);
> > + }
> > + ret = 0;
> > +
> > +out:
> > + g_rand_free(rand);
> > + return ret;
> > +}
> > +
> > +static void get_ramblock_dirty_info(RAMBlock *block,
> > + struct RamblockDirtyInfo *info,
> > + struct DirtyRateConfig *config)
> > +{
> > + uint64_t sample_pages_per_gigabytes =
> > config->sample_pages_per_gigabytes;
> > +
> > + /* Right shift 30 bits to calc block size in GB */
> > + info->sample_pages_count = (qemu_ram_get_used_length(block) *
> > + sample_pages_per_gigabytes) >>
> > + DIRTYRATE_PAGE_SHIFT_GB;
>
> Doing the calculation this way around seems odd. Why was it not:
>
> info->sample_pages_count = (qemu_ram_get_used_length(block) >>
> DIRTYRATE_PAGE_SHIFT_GB) *
> sample_pages_per_gigabytes;
>
> ?
Because that would give 0 for a 0.5GB block
Dave
> > +
> > + /* Right shift 12 bits to calc page count in 4KB */
> > + info->ramblock_pages = qemu_ram_get_used_length(block) >>
> > + DIRTYRATE_PAGE_SHIFT_KB;
> > + info->ramblock_addr = qemu_ram_get_host_addr(block);
> > + strcpy(info->idstr, qemu_ram_get_idstr(block));
> > +}
> > +
> > +static struct RamblockDirtyInfo *
> > +alloc_ramblock_dirty_info(int *block_index,
> > + struct RamblockDirtyInfo *block_dinfo)
> > +{
> > + struct RamblockDirtyInfo *info = NULL;
> > + int index = *block_index;
> > +
> > + if (!block_dinfo) {
> > + index = 0;
> > + block_dinfo = g_try_new(struct RamblockDirtyInfo, 1);
> > + } else {
> > + index++;
> > + block_dinfo = g_try_realloc(block_dinfo, (index + 1) *
> > + sizeof(struct RamblockDirtyInfo));
>
> g_try_renew() instead of g_try_realloc()?
>
> > + }
> > + if (!block_dinfo) {
> > + return NULL;
> > + }
> > +
> > + info = &block_dinfo[index];
> > + *block_index = index;
> > + memset(info, 0, sizeof(struct RamblockDirtyInfo));
> > +
> > + return block_dinfo;
> > +}
> > +
> > +static int record_ramblock_hash_info(struct RamblockDirtyInfo
> > **block_dinfo,
> > + struct DirtyRateConfig config,
> > + int *block_index)
> > +{
> > + struct RamblockDirtyInfo *info = NULL;
> > + struct RamblockDirtyInfo *dinfo = NULL;
> > + RAMBlock *block = NULL;
>
> There's no need to initialise "info" or "block".
>
> The declaration of "info" could be pushed into the loop.
>
> > + int index = 0;
> > +
> > + RAMBLOCK_FOREACH_MIGRATABLE(block) {
> > + dinfo = alloc_ramblock_dirty_info(&index, dinfo);
> > + if (dinfo == NULL) {
> > + return -1;
> > + }
> > + info = &dinfo[index];
> > + get_ramblock_dirty_info(block, info, &config);
> > + if (save_ramblock_hash(info) < 0) {
> > + *block_dinfo = dinfo;
> > + *block_index = index;
> > + return -1;
> > + }
> > + }
> > +
> > + *block_dinfo = dinfo;
> > + *block_index = index;
> > +
> > + return 0;
> > +}
> > +
> > static void calculate_dirtyrate(struct DirtyRateConfig config)
> > {
> > /* todo */
> > diff --git a/migration/dirtyrate.h b/migration/dirtyrate.h
> > index 9db269d..5050add 100644
> > --- a/migration/dirtyrate.h
> > +++ b/migration/dirtyrate.h
> > @@ -24,6 +24,21 @@
> > */
> > #define RAMBLOCK_INFO_MAX_LEN 256
> >
> > +/*
> > + * Sample page size 4K as default.
> > + */
> > +#define DIRTYRATE_SAMPLE_PAGE_SIZE 4096
> > +
> > +/*
> > + * Sample page size 4K shift
> > + */
> > +#define DIRTYRATE_PAGE_SHIFT_KB 12
> > +
> > +/*
> > + * Sample page size 1G shift
> > + */
> > +#define DIRTYRATE_PAGE_SHIFT_GB 30
> > +
> > /* Take 1s as default for calculation duration */
> > #define DEFAULT_FETCH_DIRTYRATE_TIME_SEC 1
> >
> > --
> > 1.8.3.1
>
> dme.
> --
> You bring light in.
>
--
Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
