Is there any way to shrink slab class so that space allocated at peak time can be reused for other slab classes later?
Thanks, kc 2010/11/5 Artur Ejsmont <[email protected]>: > Mikael can be right. > > Each slab is 1mb and its designated to hold items of particualr size. > So if you had 5000 items over 500KB inserted into the cache at some > time ( at the beginning ) they would consume 5GB (they would take 1MB > each even if they were 501KB). > > So after some time caching patterns change and you dont insert big > items any more. This 5GB is wasted if you are not using such big items > any more. So distribution changes and big items are not needed any > more but more smaller items cant fit into the cache as memcached cant > put small items into slabs designated for big items. > > Sorry if my explanation is not super good :) > > checkout this tool out though > http://artur.ejsmont.org/blog/content/first-version-of-memcache-stats-script-based-on-memcachephp > > i took a open source stats scripts and added detailed view of slabs. > It should tell you how many slabs you have allocated per size and how > many items are there. I guess this should give you good idea what is > really happening. > > :- ) > > art > > > > On 5 November 2010 05:59, vishnu <[email protected]> wrote: >> What is slab distribution? >> >> How can i resolve this issue? >> >> Thanks. >> >> On Thu, Nov 4, 2010 at 10:40 PM, dormando <[email protected]> wrote: >>> >>> reclaims are good, evictions are bad >>> >>> On Thu, 4 Nov 2010, Kate Wang wrote: >>> >>> > We are experiencing high reclaims instead of evictions. Could slab >>> > distribution shift cause that as well? >>> > >>> > If the slab distribution shifted could cause high eviction rate, what's >>> > the best way to fix it or avoid it? >>> > >>> > Thanks! >>> > >>> > On Thu, Nov 4, 2010 at 5:52 PM, Mikael Fridh <[email protected]> wrote: >>> > On Nov 4, 6:32 pm, rahul_kcle <[email protected]> wrote: >>> > > >>> > > From last 2 weeks i am seeing evictions happening on our >>> > memcached >>> > > boxes even though there is lot of memory left . Here are the >>> > stats >>> > > from memcached >>> > > >>> > > STAT bytes_read 434627188758 >>> > > STAT bytes_written 357821569260 >>> > > STAT limit_maxbytes 23622320128 >>> > > STAT accepting_conns 1 >>> > > STAT listen_disabled_num 0 >>> > > STAT threads 5 >>> > > STAT conn_yields 0 >>> > > STAT bytes 14573115225 >>> > > STAT curr_items 1853350 >>> > > STAT total_items 66439158 >>> > > STAT evictions 7000591 >>> > > >>> > > Bytes is much lessser than limit_maxbytes. >>> > >>> > See stats slabs, possibly your slab distribution profile have shifted >>> > over time. >>> > >>> > Mikael >>> > >>> > >>> > >>> > >> > > > > -- > Visit me at: > http://artur.ejsmont.org/blog/ >
