From mboxrd@z Thu Jan  1 00:00:00 1970
From: "changtao381" <changtao381@163.com>
Subject: journal alignment
Date: Fri, 20 Nov 2015 16:33:25 +0800
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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!