Hi All, Thanks for you apply! If directioIO + async IO requirement that alignment, it shouldn't aligned by PAGE for each journal entry. For it may write many entries of journal once time So it should do alignment after [prepare_multi_write] rather than do it each in [prepare_single_write] ? Am I right? -----邮件原件----- 发件人: Piotr.Dalek@xxxxxxxxxxxxxx [mailto:Piotr.Dalek@xxxxxxxxxxxxxx] 发送时间: 2015年11月20日 16:42 收件人: changtao381; ceph-devel@xxxxxxxxxxxxxxx 主题: RE: journal alignment > -----Original Message----- > From: ceph-devel-owner@xxxxxxxxxxxxxxx [mailto:ceph-devel- > owner@xxxxxxxxxxxxxxx] On Behalf Of changtao381 > Sent: Friday, November 20, 2015 9:33 AM > > HI All, > > Why it is needed an entry of journal t is aligned by CEPH_PAGE_MASK ? For > it causes the data of journal write are amplified by 2X for small io > > For example write io size 4096 bytes, it may write 8192 bytes > > prepare_single_write 2 will write 98304 : seq 24 len 4324 -> 8192 (head 40 > pre_pad 0 ebl 4324 post_pad 3788 tail 40) (ebl alignment -1) > > Thanks! It is a direct-IO+async IO requirement (writing on page-size boundary which is incidentally also a multiply of sector size). With best regards / Pozdrawiam Piotr Dałek -- 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
