Thanks a lot Dormando. We have made some customization to the code and we are using ITEM_data macro in order to retrieve the value of the key. This work for all slabs except the last one. Is there any way to programmatically retrieve the data ?
Thanks, Bob. On Tuesday, June 6, 2023 at 11:22:44 PM UTC+3 dormando wrote: > Hey, > > Items larger than the slab class max are "chunked" across multiple slab > chunks. See: https://github.com/memcached/memcached/wiki/ReleaseNotes1429 > > Since that release a "cap" chunk mode was added, so if chunk max is set to > 16k and you store a 17k item, it will split into: > > 1) tiny chunk for key and header > 2) 16k main chunk > 3) attempt to "cap" with a 1k chunk > > if it cannot allocate the 1k cap memory for some reason it will allocate > an extra 16k chunk instead. > > The theory is that at larger item sizes we can spend a little CPU to > improve the memory efficiency. Making the "max slab class" smaller means > we can make better use of the slab classes. At some point I will be > reducing the default setting from 512k to 256k or lower, but I need to > revisit it and add some stats counters first. > > -Dormando > > On Tue, 6 Jun 2023, boaz shavit wrote: > > > Hello,I'm trying to understand how data is saved in memcached for items > with size > 0.5M. > > When I check the slabclass structure array, I see it only has values for > classes up to .5 MB and another entry in place zero which looks like this: > > (gdb) p slabclass[0] > > $87 = {size = 0, perslab = 0, slots = 0x0, sl_curr = 0, slabs = 386, > slab_list = 0x7f15b4015ef0, list_size = 2048} > > > > when inserting a value which is very big (the key is 100 bytes, but the > value is 800k) I see that the key goes to class 2 (which is 196 bytes) but > I do > > not see where the value is stored. > > > > Can someone explain how this works for big values? > > > > Thanks in advanced, > > Bob. > > > > -- > > > > --- > > You received this message because you are subscribed to the Google > Groups "memcached" group. > > To unsubscribe from this group and stop receiving emails from it, send > an email to memcached+...@googlegroups.com. > > To view this discussion on the web visit > https://groups.google.com/d/msgid/memcached/dedecb91-b3d2-4a83-8253-0ad965cecd68n%40googlegroups.com > . > > > > -- --- You received this message because you are subscribed to the Google Groups "memcached" group. To unsubscribe from this group and stop receiving emails from it, send an email to memcached+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/memcached/e2254937-3369-4cc2-9de5-6982d1ef9066n%40googlegroups.com.