Thank you both a lot. On Tue, Jul 12, 2016 at 7:56 AM, Jason Dillaman <jdill...@redhat.com> wrote:
> All the various types of IO operations against backing objects are all > confined within AioObjectRequest.cc. At a high-level, the IO will follow > this path: > > fio -> librbd AIO API -> librbd AioImageRequestWQ [1] -> librbd > AioImageRequest (-> osdc ObjectCacher [2] -> librbd LibrbdWriteback [3]) -> > AioObjectRequest -> librados -> OSDs -> librados AIO callback [4] (-> > librbd LibrbdWriteback -> osdc ObjectCacher-> [3]) librbd AioCompletion -> > fio. > > [1] IO enters a work queue unless 'rbd_non_blocking_aio' configuration > option set to false. This option will eventually be removed once librados > is updated to ensure AIO operations cannot block (for extended periods of > time) to avoid the context switch on IO submission. > [2] If librbd cache is enabled, the fio IO operation will be immediately > completed here if 'rbd_cache_writethrough_until_flush' is set to false or > if fio is configured to send syncs). > [3] The librbd cache is single-threaded so high queue-depths can result in > a bottleneck here. > [4] librados AIO callbacks are currently single-threaded so high queue > depths can result in a bottleneck here. > > > On Tue, Jul 12, 2016 at 3:42 AM, Wido den Hollander <w...@42on.com> wrote: > >> >> > Op 12 juli 2016 om 0:28 schreef Mansour Shafaei Moghaddam < >> mansoor.shaf...@gmail.com>: >> > >> > >> > Can anyone explain or at least refer to the lines of the codes in librd >> by >> > which objects are created? I need to know the relation between objects >> and >> > fio's iodepth... >> >> Objects are not created in librados, you just write to them and they >> start to exist. >> >> So librbd simply issues a write() to RADOS regardless of the object's >> existence. >> >> Wido >> >> > >> > Thanks in advance >> > _______________________________________________ >> > ceph-users mailing list >> > ceph-users@lists.ceph.com >> > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >> _______________________________________________ >> ceph-users mailing list >> ceph-users@lists.ceph.com >> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >> > > > > -- > Jason >
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