Erez Zilber wrote:
> On Tue, Dec 15, 2009 at 10:34 AM, Mike Christie <[email protected]> wrote:
>> Erez Zilber wrote:
>>> Maintain a list of nop-out PDUs that almost timed out.
>>> With this information, you can understand and debug the
>>> whole system: you can check your target and see what caused
>>> it to be so slow on that specific time, you can see if your
>>> network was very busy during that time etc.
>>>
>>> Signed-off-by: Erez Zilber <[email protected]>
>>>
>> Sorry for the late reply. Thanks for doing this work!
>>
>>
>> @@ -88,11 +89,12 @@ static struct option const long_options[] =
>> {"killiscsid", required_argument, NULL, 'k'},
>> {"debug", required_argument, NULL, 'd'},
>> {"show", no_argument, NULL, 'S'},
>> + {"noopinfo", required_argument, NULL, 'N'},
>> {"version", no_argument, NULL, 'V'},
>> {"help", no_argument, NULL, 'h'},
>> {NULL, 0, NULL, 0},
>> };
>>
>>
>> Do you think you want something more generic like a get-debug-info type
>> of feature? Maybe in the future we could also show how many times a scsi
>> command has timed out or almost timed out (user can adjust scsi timer
>> then) or how many times the scsi eh has fired and how many times a
>> abort, lu or target reset has timed out?
>>
>> So maybe it would be get like get stats where then the noop info is the
>> first stat and in the future we will have more?
>
> Sounds good. Let's change it to {"debuginfo", required_argument, NULL, 'i'}.
> OK?
Ok with me.
>>
>>
>>
>> @@ -994,8 +997,25 @@ static int iscsi_nop_out_rsp(struct iscsi_task *task,
>> if (iscsi_recv_pdu(conn->cls_conn, (struct iscsi_hdr *)nop,
>> data, datalen))
>> rc = ISCSI_ERR_CONN_FAILED;
>> - } else
>> + } else {
>> + ping_delay = jiffies - conn->last_ping;
>> +
>> + /* Check if the ping has almost timed out */
>> + if (ping_delay >=
>> + (session->noop_threshold * (conn->ping_timeout * HZ)) /
>> + 100) {
>> + mutex_lock(&conn->noop_info_mutex);
>>
>>
>>
>> We annot use a mutex here, because we run from a bottom half (softirq
>> for iscsi and a tasklet for iser), and we cannot sleep in a bh since
>> there is no process context.
>
> You're right. I'll replace the mutex with a spinlock.
>
>>
>> + idx = conn->noop_info_arr_idx;
>> + conn->noop_info_arr[idx].tv = conn->tmp_noop_tv;
>> + conn->noop_info_arr[idx].elapsed_time_msec =
>> ping_delay;
>>
>> I think ping_delay is just in jiffies, so you have to do some sort of
>> jiffies_to_msec call (I cannot rememeber the name of the helper but
>> there is one).
>
> I think it should be: conn->noop_info_arr[idx].elapsed_time_msec =
> ping_delay * HZ / 1000
I think the function is jiffies_to_msecs()
>
>>
>> + conn->noop_info_arr[idx].init = 1;
>> + conn->noop_info_arr_idx =
>> + (conn->noop_info_arr_idx + 1) %
>> NOOP_INFO_ARR_LEN;
>>
>>
>> I am not getting the reason for the division?
>
> Are you talking about "conn->noop_info_arr_idx =
> (conn->noop_info_arr_idx + 1) % NOOP_INFO_ARR_LEN"? It's a cyclic
> array.
>
Ah, nevermind :)
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