On 19/01/12 17:32, S, Venkatraman wrote:
> On Thu, Jan 19, 2012 at 5:14 PM, Adrian Hunter <adrian.hunter@xxxxxxxxx> wrote:
>> On 19/01/12 13:33, Jaehoon Chung wrote:
>>> Hi Adrian.
>>>
>>> On 01/19/2012 07:21 PM, Adrian Hunter wrote:
>>>
>>>> On 19/01/12 07:29, Jaehoon Chung wrote:
>>>>> Enable eMMC background operations (BKOPS) feature.
>>>>>
>>>>> If URGENT_BKOPS is set after a response, note that BKOPS
>>>>> are required. After all I/O requests are finished, run
>>>>> BKOPS if required. Should read/write operations be requested
>>>>> during BKOPS, first issue HPI to interrupt the ongoing BKOPS
>>>>> and then service the request.
>>>>
>>>> This still does not seem to address my earlier comment which was:
>>>>
>>>> The main problem with bkops is:
>>>>
>>>> If the status is at level 3 ("critical"), some operations
>>>> may extend beyond their original timeouts due to maintenance
>>>> operations which cannot be delayed anymore.
>>>>
>>>> This means:
>>>>
>>>> 1. at level 3 either bkops are run or the timeout of the next
>>>> (data?) operation is extended
>>>>
>>>> 2. at level 3 either the bkops must not be interrupted or the
>>>> level must be rechecked after interruption and bkops run again
>>>> if the level is still 3, or the timeout of the next (data?)
>>>> operation is extended
>>>>
>>>
>>> This patch didn't issue the HPI when bkops-status is level2-3
>>> (URGENT_BKOPS case).
>>> I didn't understand that must be recheck?? it's case of using HPI..?
>>> If HPI didn't issue,though must be recheck bkops status?
>>> And level-1 control should be considered for future-work.
>>> I will also modify the patch comment..it's confused something.
>>
>> 1. Say there are 2 write requests queued and after the first write request
>> the bkops level is 3. That means the 2nd write request may timeout because
>> the normal timeout rules do not apply.
>>
>> Thus:
>> 1. at level 3 either bkops are run or the timeout of the next
>> (data?) operation is extended
>>
>> 2. Say you are running bkops because the level was 3 and a write request
>> arrives. You use HPI to interrupt the bkops, but the bkops level may still
>> be 3, so the write request may timeout. Hence:
>>
>> 2. at level 3 either the bkops must not be interrupted or the
>> level must be rechecked after interruption and bkops run again
>> if the level is still 3, or the timeout of the next (data?)
>> operation is extended
>>
>
> A naive question perhaps, but don't the current timeout values include
> sufficient
> buffer to do implicit garbage collection anyways ?
Maybe, but the problem is the JEDEC specification says otherwise. This bit
is a quote:
If the status is at level 3 ("critical"), some operations
may extend beyond their original timeouts due to maintenance
operations which cannot be delayed anymore.
I think level 3 is a very rare case so I would just run bkops and wait for
it to finish without interruption.
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