On 11/16/2017 01:27 AM, Jaegeuk Kim wrote: > On 11/14, Chao Yu wrote: >> On 2017/11/14 12:20, Jaegeuk Kim wrote: >>> On 11/13, Hyunchul Lee wrote: >>>> On 11/13/2017 10:59 AM, Chao Yu wrote: >>>>> On 2017/11/13 9:35, Hyunchul Lee wrote: >>>>>> On 11/13/2017 10:26 AM, Chao Yu wrote: >>>>>>> On 2017/11/13 8:24, Hyunchul Lee wrote: >>>>>>>> On 11/10/2017 03:42 PM, Chao Yu wrote: >>>>>>>>> On 2017/11/10 8:23, Hyunchul Lee wrote: >>>>>>>>>> Hello, Chao >>>>>>>>>> >>>>>>>>>> On 11/09/2017 06:12 PM, Chao Yu wrote: >>>>>>>>>>> On 2017/11/9 13:51, Hyunchul Lee wrote: >>>>>>>>>>>> From: Hyunchul Lee <cheol....@lge.com> >>>>>>>>>>>> >>>>>>>>>>>> Using write hints[1], applications can inform the life time of the >>>>>>>>>>>> data >>>>>>>>>>>> written to devices. and this[2] reported that the write hints patch >>>>>>>>>>>> decreased writes in NAND by 25%. >>>>>>>>>>>> >>>>>>>>>>>> This hints help F2FS to determine the followings. >>>>>>>>>>>> 1) the segment types where the data will be written. >>>>>>>>>>>> 2) the hints that will be passed down to devices with the data >>>>>>>>>>>> of segments. >>>>>>>>>>>> >>>>>>>>>>>> This patch set implements the first mapping from write hints to >>>>>>>>>>>> segment types >>>>>>>>>>>> as shown below. >>>>>>>>>>>> >>>>>>>>>>>> hints segment type >>>>>>>>>>>> ----- ------------ >>>>>>>>>>>> WRITE_LIFE_SHORT CURSEG_COLD_DATA >>>>>>>>>>>> WRITE_LIFE_EXTREME CURSEG_HOT_DATA >>>>>>>>>>>> others CURSEG_WARM_DATA >>>>>>>>>>>> >>>>>>>>>>>> The F2FS poliy for hot/cold seperation has precedence over this >>>>>>>>>>>> hints, And >>>>>>>>>>>> hints are not applied in in-place update. >>>>>>>>>>> >>>>>>>>>>> Could we change to disable IPU if file/inode write hint is existing? >>>>>>>>>>> >>>>>>>>>> >>>>>>>>>> I am afraid that this makes side effects. for example, this could >>>>>>>>>> cause >>>>>>>>>> out-of-place updates even when there are not enough free segments. >>>>>>>>>> I can write the patch that handles these situations. But I wonder >>>>>>>>>> that this is required, and I am not sure which IPU polices can be >>>>>>>>>> disabled. >>>>>>>>> >>>>>>>>> Oh, As I replied in another thread, I think IPU just affects >>>>>>>>> filesystem >>>>>>>>> hot/cold separating, rather than this feature. So I think it will be >>>>>>>>> okay >>>>>>>>> to not consider it. >>>>>>>>> >>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> Before the second mapping is implemented, write hints are not >>>>>>>>>>>> passed down >>>>>>>>>>>> to devices. Because it is better that the data of a segment have >>>>>>>>>>>> the same >>>>>>>>>>>> hint. >>>>>>>>>>>> >>>>>>>>>>>> [1]: c75b1d9421f80f4143e389d2d50ddfc8a28c8c35 >>>>>>>>>>>> [2]: https://lwn.net/Articles/726477/ >>>>>>>>>>> >>>>>>>>>>> Could you write a patch to support passing write hint to block >>>>>>>>>>> layer for >>>>>>>>>>> buffered writes as below commit: >>>>>>>>>>> 0127251c45ae ("ext4: add support for passing in write hints for >>>>>>>>>>> buffered writes") >>>>>>>>>>> >>>>>>>>>> >>>>>>>>>> Sure I will. I wrote it already ;) >>>>>>>>> >>>>>>>>> Cool, ;) >>>>>>>>> >>>>>>>>>> I think that datas from the same segment should be passed down with >>>>>>>>>> the same >>>>>>>>>> hint, and the following mapping is reasonable. I wonder what is your >>>>>>>>>> opinion >>>>>>>>>> about it. >>>>>>>>>> >>>>>>>>>> segment type hints >>>>>>>>>> ------------ ----- >>>>>>>>>> CURSEG_COLD_DATA WRITE_LIFE_EXTREME >>>>>>>>>> CURSEG_HOT_DATA WRITE_LIFE_SHORT >>>>>>>>>> CURSEG_COLD_NODE WRITE_LIFE_NORMAL >>>>>>>>> >>>>>>>>> We have WRITE_LIFE_LONG defined rather than WRITE_LIFE_NORMAL in fs.h? >>>>>>>>> >>>>>>>>>> CURSEG_HOT_NODE WRITE_LIFE_MEDIUM >>>>>>>>> >>>>>>>>> As I know, in scenario of cell phone, data of meta_inode is hottest, >>>>>>>>> then hot >>>>>>>>> data, warm node, and cold node should be coldest. So I suggested we >>>>>>>>> can define >>>>>>>>> as below: >>>>>>>>> >>>>>>>>> META_DATA WRITE_LIFE_SHORT >>>>>>>>> HOT_DATA & WARM_NODE WRITE_LIFE_MEDIUM >>>>>>>>> HOT_NODE & WARM_DATA WRITE_LIFE_LONG >>>>>>>>> COLD_NODE & COLD_DATA WRITE_LIFE_EXTREME >>>>>>>>> >>>>>>>> >>>>>>>> I agree, But I am not sure that assigning the same hint to a node and >>>>>>>> data >>>>>>>> segment is good. Because NVMe is likely to write them in the same >>>>>>>> erase >>>>>>>> block if they have the same hint. >>>>>>> >>>>>>> If we do not give the hint, they can still be written to the same erase >>>>>>> block, >>>>> >>>>> I mean it's possible to write them to the same erase block. :) >>>>> >>>>>>> right? it will not be worse? >>>>>>> >>>>>> >>>>>> If the hint is not given, I think that they could be written to >>>>>> the same erase block, or not. But if we give the same hint, they are >>>>>> written >>>>>> to the same block. >>>>> >>>>> IMO, Only if underlying device can support more hint type or opened >>>>> channels, >>>>> and actual temperature of data segment and node segment is quite >>>>> different, we >>>>> can separate them. >>>>> >>>> >>>> Okay, If Jaegeuk Kim agrees with this, I will submit the patch that >>>> implements your proposed mapping. >>> >>> How about this? We'd better to split data and node blocks as much as >>> possible. >>> >>> segment type hints >>> ------------ ----- >>> COLD_NODE & COLD_DATA WRITE_LIFE_NONE >> >> WRITE_LIFE_NONE means there is no hints about write life time. >> >> Shouldn't we define COLD_NODE & COLD_DATA as WRITE_LIFE_EXTERME? > > The assumption would be to split different types of blocks by flash firmware, > so I think we can use WRITE_LIFE_NONE as a type as well. >
WRITE_LIFE_NONE means that no stream id is specified. It equals WRITE_LIFE_NOT_SET. So I think that we can define WARM_DATA as WRITE_LIFE_NONE, and COLD_NODE & COLD_DATA as WRITE_LIFE_EXTREME. Thanks. > Thanks, > >> >> Thanks, >> >>> WARM_DATA WRITE_LIFE_EXTERME >>> HOT_NODE & WARM_NODE WRITE_LIFE_LONG >>> HOT_DATA WRITE_LIFE_MEDIUM >>> META_DATA WRITE_LIFE_SHORT >>> >>>> >>>> Thank you for comments ;) >>>> >>>>> Thanks, >>>>> >>>>>> I am not sure ;) >>>>>> >>>>>>> Thanks, >>>>>>> >>>>>>>> >>>>>>>> Thanks. >>>>>>>> >>>>>>>>> Thanks, >>>>>>>>> >>>>>>>>>> others WRITE_LIFE_NONE >>>>>>>>>> >>>>>>>>>>> Thanks, >>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> Hyunchul Lee (2): >>>>>>>>>>>> f2fs: apply write hints to select the type of segments for >>>>>>>>>>>> buffered >>>>>>>>>>>> write >>>>>>>>>>>> f2fs: apply write hints to select the type of segment for direct >>>>>>>>>>>> write >>>>>>>>>>>> >>>>>>>>>>>> fs/f2fs/data.c | 101 >>>>>>>>>>>> ++++++++++++++++++++++++++++++++---------------------- >>>>>>>>>>>> fs/f2fs/f2fs.h | 1 + >>>>>>>>>>>> fs/f2fs/segment.c | 14 +++++++- >>>>>>>>>>>> 3 files changed, 74 insertions(+), 42 deletions(-) >>>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>> >>>>>>>>>> Thanks >>>>>>>>>> >>>>>>>>>> . >>>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>> >>>>>>>> . >>>>>>>> >>>>>>> >>>>>>> >>>>>> >>>>>> . >>>>>> >>>>> >>>>> >>> >>> . >>> >
