2011/8/11 Shaohua Li <[email protected]>:
> 2011/8/11 Kyungmin Park <[email protected]>:
>> Hi Jens
>>
>> Now eMMC device requires the upper layer information to improve the data
>> performance and reliability.
>>
>> . Context ID
>> Using the context information, it can sort out the data internally and
>> improve the performance.
>> The main problem is that it's needed to define "What's the context".
>> Actually I expect cfq queue has own unique ID but it doesn't so decide to
>> use the pid instead
>>
>> . Data Tag
>> Using the Data Tag (1-bit information), It writes the data at SLC area when
>> it's hot data. So it can make the chip more reliable.
>> First I expect the REQ_META but current ext4 doesn't pass the WRITE_META.
>> only use the READ_META. so it needs to investigate it.
>>
>> With these characteristics, it's helpful to teach the device. After some
>> consideration. it's needed to pass out these information at request data
>> structure.
>>
>> Sample usage is following in drivers/mmc/card/block.c
>>
>> struct elevator_queue *e = md->queue.queue->elevator;
>> struct request_hint hint;
>> int ret;
>>
>> if (e->ops->elevator_get_req_hint_fn && req)
>> ret = e->ops->elevator_get_req_hint_fn(req, &hint);
> please put this to blkdev.h or similar. directly using it here
> is abnormal.
BTW, we can add a (rq->cmd_flags & REQ_ELVPRIV) check here to make
sure the request is at io scheduler.
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