Yes, You are right. But in ceph master branch, we have already prepare_entry(add padding) before sumibt_entry. If you have good idea base on this, It would be great.
2015-11-20 17:12 GMT+08:00 changtao381 <changtao...@163.com>: > 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.da...@ts.fujitsu.com [mailto:piotr.da...@ts.fujitsu.com] > 发送时间: 2015年11月20日 16:42 > 收件人: changtao381; ceph-devel@vger.kernel.org > 主题: RE: journal alignment > >> -----Original Message----- >> From: ceph-devel-ow...@vger.kernel.org [mailto:ceph-devel- >> ow...@vger.kernel.org] 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 majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Regards, xinze -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
