| Message ID | 33183CC9F5247A488A2544077AF19020815D2280@SZXEMA503-MBS.china.huawei.com |
|---|---|
| State | New |
| Headers | show |
* Gonglei (Arei) (arei.gonglei@huawei.com) wrote: > Avoid the hot pages cache replacing by others to remarkable decrease cache > missing. The counter of updating dirty bitmap is used to indicate the cached > page age. It seems worth noting that you've changed 'it_age's use - that's ok, but perhaps not obvious. Also, the change in the behaviour of cache_insert to 'fail' when it decides not to insert a page is not obvious. > Signed-off-by: ChenLiang <chenliang88@huawei.com> > Signed-off-by: Gonglei <arei.gonglei@huawei.com> > --- > arch_init.c | 8 +++++--- > include/migration/page_cache.h | 8 ++++++-- > page_cache.c | 19 +++++++++++++++---- > 3 files changed, 26 insertions(+), 9 deletions(-) > > diff --git a/arch_init.c b/arch_init.c > index 6823c5a..fc71331 100644 > --- a/arch_init.c > +++ b/arch_init.c > @@ -315,7 +315,8 @@ static void xbzrle_cache_zero_page(ram_addr_t current_addr) > > /* We don't care if this fails to allocate a new cache page > * as long as it updated an old one */ > - cache_insert(XBZRLE.cache, current_addr, ZERO_TARGET_PAGE); > + cache_insert(XBZRLE.cache, current_addr, ZERO_TARGET_PAGE, > + get_bitmap_sync_cnt()); > } > > #define ENCODING_FLAG_XBZRLE 0x1 > @@ -327,10 +328,11 @@ static int save_xbzrle_page(QEMUFile *f, uint8_t **current_data, > int encoded_len = 0, bytes_sent = -1; > uint8_t *prev_cached_page; > > - if (!cache_is_cached(XBZRLE.cache, current_addr)) { > + if (!cache_is_cached(XBZRLE.cache, current_addr, get_bitmap_sync_cnt())) { > acct_info.xbzrle_cache_miss++; > if (!last_stage) { > - if (cache_insert(XBZRLE.cache, current_addr, *current_data) == -1) { > + if (cache_insert(XBZRLE.cache, current_addr, *current_data, > + get_bitmap_sync_cnt()) == -1) { > return -1; > } else { > /* update *current_data when the page has been > diff --git a/include/migration/page_cache.h b/include/migration/page_cache.h > index 2d5ce2d..cadce55 100644 > --- a/include/migration/page_cache.h > +++ b/include/migration/page_cache.h > @@ -43,8 +43,10 @@ void cache_fini(PageCache *cache); > * > * @cache pointer to the PageCache struct > * @addr: page addr > + * @current_age indicate age of the page if cache hit > */ > -bool cache_is_cached(const PageCache *cache, uint64_t addr); > +bool cache_is_cached(const PageCache *cache, uint64_t addr, > + uint64_t current_age); > > /** > * get_cached_data: Get the data cached for an addr > @@ -65,8 +67,10 @@ uint8_t *get_cached_data(const PageCache *cache, uint64_t addr); > * @cache pointer to the PageCache struct > * @addr: page address > * @pdata: pointer to the page > + * @current_age indicate age of the page if the page is inserted into cache > */ > -int cache_insert(PageCache *cache, uint64_t addr, const uint8_t *pdata); > +int cache_insert(PageCache *cache, uint64_t addr, const uint8_t *pdata, > + uint64_t current_age); The comment on cache_insert needs changing, it currently says: * Returns -1 on error that's not true any more, it'll return -1 on error or if it just decided that it's better not to cache it. > /** > * cache_resize: resize the page cache. In case of size reduction the extra > diff --git a/page_cache.c b/page_cache.c > index b033681..fa58ab2 100644 > --- a/page_cache.c > +++ b/page_cache.c > @@ -121,7 +121,8 @@ static size_t cache_get_cache_pos(const PageCache *cache, > return pos; > } > > -bool cache_is_cached(const PageCache *cache, uint64_t addr) > +bool cache_is_cached(const PageCache *cache, uint64_t addr, > + uint64_t current_age) > { > size_t pos; > > @@ -130,7 +131,12 @@ bool cache_is_cached(const PageCache *cache, uint64_t addr) > > pos = cache_get_cache_pos(cache, addr); > > - return (cache->page_cache[pos].it_addr == addr); > + if (cache->page_cache[pos].it_addr == addr) { > + /* updata the it_age when the cache hit */ Typo: updata -> update > + cache->page_cache[pos].it_age = current_age; > + return true; > + } > + return false; > } > > static CacheItem *cache_get_by_addr(const PageCache *cache, uint64_t addr) > @@ -150,7 +156,8 @@ uint8_t *get_cached_data(const PageCache *cache, uint64_t addr) > return cache_get_by_addr(cache, addr)->it_data; > } > > -int cache_insert(PageCache *cache, uint64_t addr, const uint8_t *pdata) > +int cache_insert(PageCache *cache, uint64_t addr, const uint8_t *pdata, > + uint64_t current_age) > { > > CacheItem *it = NULL; > @@ -161,6 +168,10 @@ int cache_insert(PageCache *cache, uint64_t addr, const uint8_t *pdata) > /* actual update of entry */ > it = cache_get_by_addr(cache, addr); > > + if ((it->it_data != NULL) && (it->it_age + 2 > current_age)) { > + /* the cache page is fresh, don't replace it */ > + return -1; > + } A magical constant '2' - should probably a define/const somewhere. > /* allocate page */ > if (!it->it_data) { > it->it_data = g_try_malloc(cache->page_size); > @@ -173,7 +184,7 @@ int cache_insert(PageCache *cache, uint64_t addr, const uint8_t *pdata) > > memcpy(it->it_data, pdata, cache->page_size); > > - it->it_age = ++cache->max_item_age; > + it->it_age = current_age; > it->it_addr = addr; > > return 0; Dave -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
On 2014/2/28 17:51, Dr. David Alan Gilbert wrote: > * Gonglei (Arei) (arei.gonglei@huawei.com) wrote: >> Avoid the hot pages cache replacing by others to remarkable decrease cache >> missing. The counter of updating dirty bitmap is used to indicate the cached >> page age. > > It seems worth noting that you've changed 'it_age's use - that's ok, but > perhaps not obvious. > > Also, the change in the behaviour of cache_insert to 'fail' when it decides > not to insert a page is not obvious. > Check it. > >> Signed-off-by: ChenLiang <chenliang88@huawei.com> >> Signed-off-by: Gonglei <arei.gonglei@huawei.com> >> --- >> arch_init.c | 8 +++++--- >> include/migration/page_cache.h | 8 ++++++-- >> page_cache.c | 19 +++++++++++++++---- >> 3 files changed, 26 insertions(+), 9 deletions(-) >> >> diff --git a/arch_init.c b/arch_init.c >> index 6823c5a..fc71331 100644 >> --- a/arch_init.c >> +++ b/arch_init.c >> @@ -315,7 +315,8 @@ static void xbzrle_cache_zero_page(ram_addr_t current_addr) >> >> /* We don't care if this fails to allocate a new cache page >> * as long as it updated an old one */ >> - cache_insert(XBZRLE.cache, current_addr, ZERO_TARGET_PAGE); >> + cache_insert(XBZRLE.cache, current_addr, ZERO_TARGET_PAGE, >> + get_bitmap_sync_cnt()); >> } >> >> #define ENCODING_FLAG_XBZRLE 0x1 >> @@ -327,10 +328,11 @@ static int save_xbzrle_page(QEMUFile *f, uint8_t **current_data, >> int encoded_len = 0, bytes_sent = -1; >> uint8_t *prev_cached_page; >> >> - if (!cache_is_cached(XBZRLE.cache, current_addr)) { >> + if (!cache_is_cached(XBZRLE.cache, current_addr, get_bitmap_sync_cnt())) { >> acct_info.xbzrle_cache_miss++; >> if (!last_stage) { >> - if (cache_insert(XBZRLE.cache, current_addr, *current_data) == -1) { >> + if (cache_insert(XBZRLE.cache, current_addr, *current_data, >> + get_bitmap_sync_cnt()) == -1) { >> return -1; >> } else { >> /* update *current_data when the page has been >> diff --git a/include/migration/page_cache.h b/include/migration/page_cache.h >> index 2d5ce2d..cadce55 100644 >> --- a/include/migration/page_cache.h >> +++ b/include/migration/page_cache.h >> @@ -43,8 +43,10 @@ void cache_fini(PageCache *cache); >> * >> * @cache pointer to the PageCache struct >> * @addr: page addr >> + * @current_age indicate age of the page if cache hit >> */ >> -bool cache_is_cached(const PageCache *cache, uint64_t addr); >> +bool cache_is_cached(const PageCache *cache, uint64_t addr, >> + uint64_t current_age); >> >> /** >> * get_cached_data: Get the data cached for an addr >> @@ -65,8 +67,10 @@ uint8_t *get_cached_data(const PageCache *cache, uint64_t addr); >> * @cache pointer to the PageCache struct >> * @addr: page address >> * @pdata: pointer to the page >> + * @current_age indicate age of the page if the page is inserted into cache >> */ >> -int cache_insert(PageCache *cache, uint64_t addr, const uint8_t *pdata); >> +int cache_insert(PageCache *cache, uint64_t addr, const uint8_t *pdata, >> + uint64_t current_age); > > The comment on cache_insert needs changing, it currently says: > * Returns -1 on error > > that's not true any more, it'll return -1 on error or if it just decided > that it's better not to cache it. > Check. >> /** >> * cache_resize: resize the page cache. In case of size reduction the extra >> diff --git a/page_cache.c b/page_cache.c >> index b033681..fa58ab2 100644 >> --- a/page_cache.c >> +++ b/page_cache.c >> @@ -121,7 +121,8 @@ static size_t cache_get_cache_pos(const PageCache *cache, >> return pos; >> } >> >> -bool cache_is_cached(const PageCache *cache, uint64_t addr) >> +bool cache_is_cached(const PageCache *cache, uint64_t addr, >> + uint64_t current_age) >> { >> size_t pos; >> >> @@ -130,7 +131,12 @@ bool cache_is_cached(const PageCache *cache, uint64_t addr) >> >> pos = cache_get_cache_pos(cache, addr); >> >> - return (cache->page_cache[pos].it_addr == addr); >> + if (cache->page_cache[pos].it_addr == addr) { >> + /* updata the it_age when the cache hit */ > > Typo: updata -> update > >> + cache->page_cache[pos].it_age = current_age; >> + return true; >> + } >> + return false; >> } >> >> static CacheItem *cache_get_by_addr(const PageCache *cache, uint64_t addr) >> @@ -150,7 +156,8 @@ uint8_t *get_cached_data(const PageCache *cache, uint64_t addr) >> return cache_get_by_addr(cache, addr)->it_data; >> } >> >> -int cache_insert(PageCache *cache, uint64_t addr, const uint8_t *pdata) >> +int cache_insert(PageCache *cache, uint64_t addr, const uint8_t *pdata, >> + uint64_t current_age) >> { >> >> CacheItem *it = NULL; >> @@ -161,6 +168,10 @@ int cache_insert(PageCache *cache, uint64_t addr, const uint8_t *pdata) >> /* actual update of entry */ >> it = cache_get_by_addr(cache, addr); >> >> + if ((it->it_data != NULL) && (it->it_age + 2 > current_age)) { >> + /* the cache page is fresh, don't replace it */ >> + return -1; >> + } > > A magical constant '2' - should probably a define/const somewhere. Check. > >> /* allocate page */ >> if (!it->it_data) { >> it->it_data = g_try_malloc(cache->page_size); >> @@ -173,7 +184,7 @@ int cache_insert(PageCache *cache, uint64_t addr, const uint8_t *pdata) >> >> memcpy(it->it_data, pdata, cache->page_size); >> >> - it->it_age = ++cache->max_item_age; >> + it->it_age = current_age; >> it->it_addr = addr; >> >> return 0; > > Dave > -- > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK Best regards, -Gonglei
diff --git a/arch_init.c b/arch_init.c index 6823c5a..fc71331 100644 --- a/arch_init.c +++ b/arch_init.c @@ -315,7 +315,8 @@ static void xbzrle_cache_zero_page(ram_addr_t current_addr) /* We don't care if this fails to allocate a new cache page * as long as it updated an old one */ - cache_insert(XBZRLE.cache, current_addr, ZERO_TARGET_PAGE); + cache_insert(XBZRLE.cache, current_addr, ZERO_TARGET_PAGE, + get_bitmap_sync_cnt()); } #define ENCODING_FLAG_XBZRLE 0x1 @@ -327,10 +328,11 @@ static int save_xbzrle_page(QEMUFile *f, uint8_t **current_data, int encoded_len = 0, bytes_sent = -1; uint8_t *prev_cached_page; - if (!cache_is_cached(XBZRLE.cache, current_addr)) { + if (!cache_is_cached(XBZRLE.cache, current_addr, get_bitmap_sync_cnt())) { acct_info.xbzrle_cache_miss++; if (!last_stage) { - if (cache_insert(XBZRLE.cache, current_addr, *current_data) == -1) { + if (cache_insert(XBZRLE.cache, current_addr, *current_data, + get_bitmap_sync_cnt()) == -1) { return -1; } else { /* update *current_data when the page has been diff --git a/include/migration/page_cache.h b/include/migration/page_cache.h index 2d5ce2d..cadce55 100644 --- a/include/migration/page_cache.h +++ b/include/migration/page_cache.h @@ -43,8 +43,10 @@ void cache_fini(PageCache *cache); * * @cache pointer to the PageCache struct * @addr: page addr + * @current_age indicate age of the page if cache hit */ -bool cache_is_cached(const PageCache *cache, uint64_t addr); +bool cache_is_cached(const PageCache *cache, uint64_t addr, + uint64_t current_age); /** * get_cached_data: Get the data cached for an addr @@ -65,8 +67,10 @@ uint8_t *get_cached_data(const PageCache *cache, uint64_t addr); * @cache pointer to the PageCache struct * @addr: page address * @pdata: pointer to the page + * @current_age indicate age of the page if the page is inserted into cache */ -int cache_insert(PageCache *cache, uint64_t addr, const uint8_t *pdata); +int cache_insert(PageCache *cache, uint64_t addr, const uint8_t *pdata, + uint64_t current_age); /** * cache_resize: resize the page cache. In case of size reduction the extra diff --git a/page_cache.c b/page_cache.c index b033681..fa58ab2 100644 --- a/page_cache.c +++ b/page_cache.c @@ -121,7 +121,8 @@ static size_t cache_get_cache_pos(const PageCache *cache, return pos; } -bool cache_is_cached(const PageCache *cache, uint64_t addr) +bool cache_is_cached(const PageCache *cache, uint64_t addr, + uint64_t current_age) { size_t pos; @@ -130,7 +131,12 @@ bool cache_is_cached(const PageCache *cache, uint64_t addr) pos = cache_get_cache_pos(cache, addr); - return (cache->page_cache[pos].it_addr == addr); + if (cache->page_cache[pos].it_addr == addr) { + /* updata the it_age when the cache hit */ + cache->page_cache[pos].it_age = current_age; + return true; + } + return false; } static CacheItem *cache_get_by_addr(const PageCache *cache, uint64_t addr) @@ -150,7 +156,8 @@ uint8_t *get_cached_data(const PageCache *cache, uint64_t addr) return cache_get_by_addr(cache, addr)->it_data; } -int cache_insert(PageCache *cache, uint64_t addr, const uint8_t *pdata) +int cache_insert(PageCache *cache, uint64_t addr, const uint8_t *pdata, + uint64_t current_age) { CacheItem *it = NULL; @@ -161,6 +168,10 @@ int cache_insert(PageCache *cache, uint64_t addr, const uint8_t *pdata) /* actual update of entry */ it = cache_get_by_addr(cache, addr); + if ((it->it_data != NULL) && (it->it_age + 2 > current_age)) { + /* the cache page is fresh, don't replace it */ + return -1; + } /* allocate page */ if (!it->it_data) { it->it_data = g_try_malloc(cache->page_size); @@ -173,7 +184,7 @@ int cache_insert(PageCache *cache, uint64_t addr, const uint8_t *pdata) memcpy(it->it_data, pdata, cache->page_size); - it->it_age = ++cache->max_item_age; + it->it_age = current_age; it->it_addr = addr; return 0;