[Sheepdog] [PATCH V3] Make the flushing data more fine grained
Yunkai Zhang
yunkai.me at gmail.com
Tue May 15 10:33:16 CEST 2012
On Tue, May 15, 2012 at 4:13 PM, Liu Yuan <namei.unix at gmail.com> wrote:
> On 05/14/2012 09:56 PM, Yunkai Zhang wrote:
>
>> From: Yunkai Zhang <qiushu.zyk at taobao.com>
>>
>> Each time when sheep flushes an cache object, it will flush its whole
>> data(4M) to the cluster, even if that object only contains one byte in
>> dirty.
>>
>> Now I splits an cache object into multiple blocks, each block is 128 KB
>> (this size can be switch in range[64, 128, 256, 512] KB defined by BLOCK_SIZE
>> macro).
>>
>> Each time when client writes an cache object, sheep will caculate which block
>> would be modified and mark it as dirty block. Those dirty infomation are saved
>> in a bitmap.
>>
>> When sheep flushes an canch object, it will not flush the whole data again,
>> instead of, it will read the bitmap of this object and only send the data marked
>> as dirty block.
>>
>> In addition, I replaced flock with lockf so that we only lock on the section we
>> care about of an object file.
>>
>> Signed-off-by: Yunkai Zhang <qiushu.zyk at taobao.com>
>> ---
>> - BLOCK_SIZE to CACHE_BLOCK_SIZE
>> - object_bmap_calc to calc_object_bmap
>> - changes flush algo.
>> - fix bugs when push vdi object
>> include/util.h | 10 +++++
>> sheep/object_cache.c | 98 +++++++++++++++++++++++++++++++++++++++++---------
>> sheep/sheep_priv.h | 3 ++
>> 3 files changed, 94 insertions(+), 17 deletions(-)
>>
>> diff --git a/include/util.h b/include/util.h
>> index ca43ab9..1c32954 100644
>> --- a/include/util.h
>> +++ b/include/util.h
>> @@ -4,6 +4,7 @@
>> #include <string.h>
>> #include <limits.h>
>> #include <stdint.h>
>> +#include <unistd.h>
>>
>> #include "bitops.h"
>> #include "list.h"
>> @@ -58,6 +59,15 @@ static inline void *zalloc(size_t size)
>> return calloc(1, size);
>> }
>>
>> +static inline int xlockf(int fd, int cmd, off_t offset, off_t len)
>> +{
>> + if (lseek(fd, offset, SEEK_SET) < 0)
>> + return -1;
>> +
>> + return lockf(fd, cmd, len);
>> +}
>> +
>> +
>> typedef void (*try_to_free_t)(size_t);
>> extern try_to_free_t set_try_to_free_routine(try_to_free_t);
>>
>> diff --git a/sheep/object_cache.c b/sheep/object_cache.c
>> index 0b3c911..4d3864c 100644
>> --- a/sheep/object_cache.c
>> +++ b/sheep/object_cache.c
>> @@ -41,6 +41,24 @@ static inline int hash(uint64_t vid)
>> return hash_64(vid, HASH_BITS);
>> }
>>
>> +static uint64_t calc_object_bmap(size_t len, off_t offset)
>> +{
>> + int i, j;
>> + uint64_t bmap, shift = 1;
>> +
>> + if (!len)
>> + return 0;
>> +
>> + i = offset / CACHE_BLOCK_SIZE;
>> + j = (offset + len - 1) / CACHE_BLOCK_SIZE;
>> +
>> + bmap = (shift <<= i);
>> + while (j - i++)
>> + bmap |= (shift <<= 1);
>> +
>> + return bmap;
>> +}
>> +
>
>
> I think this code is a little bit confusing, normally shift has a common
> sense of how many bits we shift. But I am okay for this, since it is
> matter of personal taste.
>
>> static struct object_cache_entry *dirty_tree_insert(struct rb_root *root,
>> struct object_cache_entry *new)
>> {
>> @@ -56,8 +74,11 @@ static struct object_cache_entry *dirty_tree_insert(struct rb_root *root,
>> p = &(*p)->rb_left;
>> else if (new->idx > entry->idx)
>> p = &(*p)->rb_right;
>> - else
>> - return entry; /* already has this entry */
>> + else {
>> + /* already has this entry, merge bmap */
>> + entry->bmap |= new->bmap;
>> + return entry;
>> + }
>> }
>> rb_link_node(&new->rb, parent, p);
>> rb_insert_color(&new->rb, root);
>> @@ -143,11 +164,12 @@ out:
>> }
>>
>> static void add_to_dirty_tree_and_list(struct object_cache *oc, uint32_t idx,
>> - struct object_cache_entry *entry, int create)
>> + uint64_t bmap, struct object_cache_entry *entry, int create)
>> {
>> if (!entry) {
>> entry = xzalloc(sizeof(*entry));
>> entry->idx = idx;
>> + entry->bmap = bmap;
>> entry->create = create;
>> }
>> if (!dirty_tree_insert(oc->active_dirty_tree, entry))
>> @@ -194,7 +216,8 @@ static void merge_dirty_tree_and_list(struct object_cache *oc,
>>
>> list_for_each_entry_safe(entry, t, inactive_dirty_list, list) {
>> del_from_dirty_tree_and_list(entry, inactive_dirty_tree);
>> - add_to_dirty_tree_and_list(oc, entry->idx, entry, 0);
>> + add_to_dirty_tree_and_list(oc, entry->idx,
>> + entry->bmap, entry, 0);
>
>
> It seems that we don't need to pass entry->bmap for
> add_to_dirty_tree_and_list()
We need it! If there are nodes with the same idx in active_ditry_tree,
entry->bmap would be merged with that nodes so that dirty blocks info
would not be lost.
>
>
>> }
>>
>> pthread_mutex_unlock(&oc->lock);
>> @@ -230,7 +253,7 @@ int object_cache_lookup(struct object_cache *oc, uint32_t idx, int create)
>> ret = -1;
>> else {
>> pthread_mutex_lock(&oc->lock);
>> - add_to_dirty_tree_and_list(oc, idx, NULL, 1);
>> + add_to_dirty_tree_and_list(oc, idx, 0, NULL, 1);
>> pthread_mutex_unlock(&oc->lock);
>> }
>> }
>> @@ -254,13 +277,13 @@ static int write_cache_object(uint32_t vid, uint32_t idx, void *buf, size_t coun
>> flags |= O_DIRECT;
>>
>> fd = open(p.buf, flags, def_fmode);
>> - if (flock(fd, LOCK_EX) < 0) {
>> + if (xlockf(fd, F_LOCK, offset, count) < 0) {
>> ret = SD_RES_EIO;
>> eprintf("%m\n");
>> goto out;
>> }
>> size = xpwrite(fd, buf, count, offset);
>> - if (flock(fd, LOCK_UN) < 0) {
>> + if (xlockf(fd, F_UNLCK, offset, count) < 0) {
>> ret = SD_RES_EIO;
>> eprintf("%m\n");
>> goto out;
>> @@ -287,14 +310,14 @@ static int read_cache_object(uint32_t vid, uint32_t idx, void *buf, size_t count
>> flags |= O_DIRECT;
>>
>> fd = open(p.buf, flags, def_fmode);
>> - if (flock(fd, LOCK_SH) < 0) {
>> + if (xlockf(fd, F_LOCK, offset, count) < 0) {
>> ret = SD_RES_EIO;
>> eprintf("%m\n");
>> goto out;
>> }
>>
>> size = xpread(fd, buf, count, offset);
>> - if (flock(fd, LOCK_UN) < 0) {
>> + if (xlockf(fd, F_UNLCK, offset, count) < 0) {
>> ret = SD_RES_EIO;
>> eprintf("%m\n");
>> goto out;
>> @@ -311,6 +334,7 @@ int object_cache_rw(struct object_cache *oc, uint32_t idx, struct request *req)
>> {
>> struct sd_obj_req *hdr = (struct sd_obj_req *)&req->rq;
>> struct sd_obj_rsp *rsp = (struct sd_obj_rsp *)&req->rp;
>> + uint64_t bmap = 0;
>> int ret;
>>
>> dprintf("%08"PRIx32", len %"PRIu32", off %"PRIu64"\n", idx, hdr->data_length, hdr->offset);
>> @@ -319,7 +343,8 @@ int object_cache_rw(struct object_cache *oc, uint32_t idx, struct request *req)
>> if (ret != SD_RES_SUCCESS)
>> goto out;
>> pthread_mutex_lock(&oc->lock);
>> - add_to_dirty_tree_and_list(oc, idx, NULL, 0);
>> + bmap = calc_object_bmap(hdr->data_length, hdr->offset);
>> + add_to_dirty_tree_and_list(oc, idx, bmap, NULL, 0);
>> pthread_mutex_unlock(&oc->lock);
>> } else {
>> ret = read_cache_object(oc->vid, idx, req->data, hdr->data_length, hdr->offset);
>> @@ -476,22 +501,59 @@ static uint64_t idx_to_oid(uint32_t vid, uint32_t idx)
>> return vid_to_data_oid(vid, idx);
>> }
>>
>> -static int push_cache_object(uint32_t vid, uint32_t idx, int create)
>> +static int push_cache_object(uint32_t vid, uint32_t idx,
>> + uint64_t bmap, int create)
>> {
>> struct request fake_req;
>> struct sd_obj_req *hdr = (struct sd_obj_req *)&fake_req.rq;
>> void *buf;
>> + off_t offset;
>> unsigned data_length;
>> int ret = SD_RES_NO_MEM;
>> - uint64_t oid = idx_to_oid(vid, idx);
>> + uint64_t shift, oid = idx_to_oid(vid, idx);
>> + int i, nbits, first_dirty_bit, last_dirty_bit;
>>
>> dprintf("%"PRIx64", create %d\n", oid, create);
>>
>> + if (!bmap)
>> + return SD_RES_SUCCESS;
>> +
>> memset(&fake_req, 0, sizeof(fake_req));
>> if (is_vdi_obj(oid))
>> - data_length = SD_INODE_SIZE;
>> + nbits = DIV_ROUND_UP(SD_INODE_SIZE, CACHE_BLOCK_SIZE);
>> else
>> - data_length = SD_DATA_OBJ_SIZE;
>> + nbits = DIV_ROUND_UP(SD_DATA_OBJ_SIZE, CACHE_BLOCK_SIZE);
>> +
>> + shift = 1;
>> + first_dirty_bit = 0;
>> +
>> + for (i = 0; i < nbits; i++) {
>> + if (bmap & (shift << i)) {
>> + first_dirty_bit = i;
>> + break;
>> + }
>> + }
>> +
>> + shift = (UINT64_C(1) << (nbits - 1));
>> + last_dirty_bit = 0;
>> + for (i = 0; i < nbits; i++) {
>> + if (bmap & (shift >> i)) {
>> + last_dirty_bit = nbits - i - 1 ;
>> + break;
>> + }
>> + }
>> +
>> + dprintf("bmap:0x%"PRIx64", first_dirty_bit:%d, last_dirty_bit:%d\n",
>> + bmap, first_dirty_bit, last_dirty_bit);
>> + offset = first_dirty_bit * CACHE_BLOCK_SIZE;
>> + data_length = (last_dirty_bit - first_dirty_bit + 1) * CACHE_BLOCK_SIZE;
>> +
>> + /*
>> + * CACHE_BLOCK_SIZE may not be divisible by SD_INODE_SIZE,
>> + * so data_length could larger than SD_INODE_SIZE
>> + */
>> + if (is_vdi_obj(oid) && data_length > SD_INODE_SIZE)
>> + data_length = SD_INODE_SIZE;
>>
>> buf = valloc(data_length);
>> if (buf == NULL) {
>> @@ -499,7 +561,7 @@ static int push_cache_object(uint32_t vid, uint32_t idx, int create)
>> goto out;
>> }
>>
>> - ret = read_cache_object(vid, idx, buf, data_length, 0);
>> + ret = read_cache_object(vid, idx, buf, data_length, offset);
>> if (ret != SD_RES_SUCCESS)
>> goto out;
>>
>> @@ -546,7 +608,8 @@ int object_cache_push(struct object_cache *oc)
>> * request is issued in one of gateway worker threads
>> * So we need not to protect inactive dirty tree and list */
>> list_for_each_entry_safe(entry, t, inactive_dirty_list, list) {
>> - ret = push_cache_object(oc->vid, entry->idx, entry->create);
>> + ret = push_cache_object(oc->vid, entry->idx,
>> + entry->bmap, entry->create);
>> if (ret != SD_RES_SUCCESS)
>> goto push_failed;
>> del_from_dirty_tree_and_list(entry, inactive_dirty_tree);
>> @@ -614,6 +677,7 @@ int object_cache_flush_and_delete(struct object_cache *oc)
>> struct dirent *d;
>> uint32_t vid = oc->vid;
>> uint32_t idx;
>> + uint64_t bmap = 0;
>> struct strbuf p;
>> int ret = 0;
>>
>> @@ -635,7 +699,7 @@ int object_cache_flush_and_delete(struct object_cache *oc)
>> idx = strtoul(d->d_name, NULL, 16);
>> if (idx == ULLONG_MAX)
>> continue;
>> - if (push_cache_object(vid, idx, 1) != SD_RES_SUCCESS) {
>> + if (push_cache_object(vid, idx, ~bmap, 1) != SD_RES_SUCCESS) {
>
>
> Better use another var (for e.g, all = ~0 ) to means to flush the whole
No, There was not type info with ~0, it's size depends on system
environment, we should keep it as 64 bit, so I use ~bmap variable
instead.
> object, instead of '~bmap',
>
> Thanks,
> Yuan
--
Yunkai Zhang
Work at Taobao
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