Hi Kent, i am sorry to bother you again. i am reading the movinggc.c, i am really interested in this piece of codes. So if i enable the copy_gc, this piece of codes will be active. My question is after the gc_moving confirmed the gc_moving_threshold, it began to scan the bkeys. i do not quite understand how you fill the moving_gc_keys, do you go through all the current btree nodes to find proper keys for migration (the bucket.used_sectors < threshold)? or you do incremental scans? i will be appreciated if you can explain some more about it. Thanks, Sheng On Wed, Jul 10, 2013 at 11:22 AM, sheng qiu <herbert1984106@xxxxxxxxx> wrote: > Hi Kent, > > just a quick question about the bkey fields. The "high" member seems > to have some bits not used right now. from bits 37 to bits 54 seems to > be unused, right? > The reason i was asking is that i want to keep some additional > information in the bkeys, if these bits are not used i might reuse > them without incur more storage. > > Thanks, > Sheng > > On Tue, Jul 9, 2013 at 11:24 AM, sheng qiu <herbert1984106@xxxxxxxxx> wrote: >> Hi Kent, >> >> thanks for reply. i read the document in the code. just to make sure i >> understand correctly, the stale key nodes are produced by invalidation >> (replacement) of the buckets they reside on, right? >> in another word, the stale key nodes might be the recently evict out data? >> >> Thanks, >> Sheng >> >> On Mon, Jul 8, 2013 at 5:48 PM, Kent Overstreet <kmo@xxxxxxxxxxxxx> wrote: >>> On Mon, Jul 08, 2013 at 09:44:41AM -0400, sheng qiu wrote: >>>> Hi Kent, >>>> >>>> Thanks a lot for your reply. >>>> >>>> Then i have a question about the bucket invalidation. when bcache >>>> choose to replace a bucket, will the keys that reside on that bucket >>>> still be in the btree? since you do not have information about which >>>> keys reside on the bucket, how do you update the btree? >>>> >>>> i can think out two ways, one is you periodically scan the btree nodes >>>> and delete the stale nodes, the other way is when you get a cache hit >>>> on stale nodes, then you delete it at that moment. How bcache does >>>> this? Can you tell me the functions involve for these operations? i am >>>> interested in this part of codes. >>> >>> This is documented in the code - start here: >>> http://evilpiepirate.org/git/linux-bcache.git/tree/drivers/md/bcache/bcache.h?h=bcache-dev >> >> >> >> -- >> Sheng Qiu >> Texas A & M University >> Room 332B Wisenbaker >> email: herbert1984106@xxxxxxxxx >> College Station, TX 77843-3259 > > > > -- > Sheng Qiu > Texas A & M University > Room 332B Wisenbaker > email: herbert1984106@xxxxxxxxx > College Station, TX 77843-3259 -- Sheng Qiu Texas A & M University Room 332B Wisenbaker email: herbert1984106@xxxxxxxxx College Station, TX 77843-3259 -- To unsubscribe from this list: send the line "unsubscribe linux-bcache" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
