Hi, i am trying to understand the ceph codes on client side. for write path, if it's aio_write, the ceph_write_begin() allocate pages in page cache to buffer the written data, however i did not see it allocated any space on the remote OSDs (for local fs such as ext2, the get_block() did this), i suppose it's done later when invoke kernel flushing process to write back the dirty pages. i checked the ceph_writepages_start(), here it seems organize the dirty data and prepare the requests to send to the OSDs. For new allocated written data, how it maps to the OSDs and where it is done? is it done in ceph_osdc_new_request()? If the transfer unit is not limited to sizes of obj, i supposed that ceph needed to packed several pieces of data (smaller than one obj size) together so that there won't be internal fragmentation for an object. who does this job and which part of source codes/files are related with this? I really want to get a deep understanding about the codes, so i raised these questions. if my understanding is not correct, please figure out. i will be very appreciated. Thanks, Sheng -- 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 ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
