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Message-ID: <63eb3af9e7721a617fa922e4b9af00ec@codeaurora.org>
Date: Tue, 13 Dec 2016 13:00:00 -0800
From: Subhash Jadavani <subhashj@...eaurora.org>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: vinholikatti@...il.com, jejb@...ux.vnet.ibm.com,
martin.petersen@...cle.com, linux-scsi@...r.kernel.org,
Lee Susman <lsusman@...eaurora.org>,
Ingo Molnar <mingo@...hat.com>,
Sahitya Tummala <stummala@...eaurora.org>,
Venkat Gopalakrishnan <venkatg@...eaurora.org>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 11/12] scsi: ufs: add trace event for ufs commands
On 2016-12-13 12:22, Steven Rostedt wrote:
> On Tue, 13 Dec 2016 11:52:16 -0800
> Subhash Jadavani <subhashj@...eaurora.org> wrote:
>
>> From: Lee Susman <lsusman@...eaurora.org>
>>
>> Use the ftrace infrastructure to conditionally trace ufs command
>> events.
>> New trace event is created, which samples the following ufs command
>> data:
>> - device name
>> - optional identification string
>> - task tag
>> - doorbell register
>> - number of transfer bytes
>> - interrupt status register
>> - request start LBA
>> - command opcode
>>
>> Currently we only fully trace read(10) and write(10) commands.
>> All other commands which pass through ufshcd_send_command() will be
>> printed with "-1" in the lba and transfer_len fields.
>>
>> Usage:
>> echo 1 > /sys/kernel/debug/tracing/events/ufs/enable
>> cat /sys/kernel/debug/tracing/trace_pipe
>>
>> Signed-off-by: Lee Susman <lsusman@...eaurora.org>
>> Signed-off-by: Subhash Jadavani <subhashj@...eaurora.org>
>> ---
>> drivers/scsi/ufs/ufshcd.c | 52
>> +++++++++++++++++++++++++++++++++++++++++++++-
>> include/trace/events/ufs.h | 38 +++++++++++++++++++++++++++++++++
>> 2 files changed, 89 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
>> index 33f3947..926d1ef 100644
>> --- a/drivers/scsi/ufs/ufshcd.c
>> +++ b/drivers/scsi/ufs/ufshcd.c
>> @@ -301,6 +301,51 @@ static inline void
>> ufshcd_remove_non_printable(char *val)
>> *val = ' ';
>> }
>>
>> +#ifdef CONFIG_TRACEPOINTS
>> +static void ufshcd_add_command_trace(struct ufs_hba *hba,
>> + unsigned int tag, const char *str)
>
> Is this function only to use if you enable the tracepoint? Is there
> anything here doing something that wouldn't be enabled if tracing
> wasn't configured in?
>
> Also, if this is in a code execution path, it appears that you do this
> work regardless if the tracer is running or not.
That's true, need to fix this.
>
>> +{
>> + sector_t lba = -1;
>> + u8 opcode = 0;
>> + u32 intr, doorbell;
>> + struct ufshcd_lrb *lrbp;
>> + int transfer_len = -1;
>> +
>> + lrbp = &hba->lrb[tag];
>> +
>> + if (lrbp->cmd) { /* data phase exists */
>> + opcode = (u8)(*lrbp->cmd->cmnd);
>> + if ((opcode == READ_10) || (opcode == WRITE_10)) {
>> + /*
>> + * Currently we only fully trace read(10) and write(10)
>> + * commands
>> + */
>> + if (lrbp->cmd->request && lrbp->cmd->request->bio)
>> + lba =
>> + lrbp->cmd->request->bio->bi_iter.bi_sector;
>> + transfer_len = be32_to_cpu(
>> + lrbp->ucd_req_ptr->sc.exp_data_transfer_len);
>> + }
>> + }
>> +
>> + intr = ufshcd_readl(hba, REG_INTERRUPT_STATUS);
>> + doorbell = ufshcd_readl(hba, REG_UTP_TRANSFER_REQ_DOOR_BELL);
>> + trace_ufshcd_command(dev_name(hba->dev), str, tag,
>> + doorbell, transfer_len, intr, lba, opcode);
>> +}
>> +
>> +static inline void ufshcd_cond_add_cmd_trace(struct ufs_hba *hba,
>> + unsigned int tag, const char *str)
>> +{
>> + ufshcd_add_command_trace(hba, tag, str);
>> +}
>> +#else
>> +static inline void ufshcd_cond_add_cmd_trace(struct ufs_hba *hba,
>> + unsigned int tag, const char *str)
>> +{
>> +}
>> +#endif
>
> If my above assumptions are correct, I recommend removing the above
> #if, and have it always configured. Then...
Agreed.
>
>> +
>> static void ufshcd_print_host_regs(struct ufs_hba *hba)
>> {
>> /*
>> @@ -1193,6 +1238,7 @@ void ufshcd_send_command(struct ufs_hba *hba,
>> unsigned int task_tag)
>> ufshcd_writel(hba, 1 << task_tag, REG_UTP_TRANSFER_REQ_DOOR_BELL);
>> /* Make sure that doorbell is committed immediately */
>> wmb();
>
> Add:
>
> if (trace_ufshcd_command_enabled())
> ufshcd_cond_add_cmd_trace(hba, task_tag, "send");
>
> For one thing, the function only gets called if the tracepoint
> ufshcd_command is enabled.
>
> Now if CONFIG_TRACEPOINTS is not configured in, then the
> trace_ufshcd_command_enabled() turns into a "return false;" which one
> would hope that gcc will take that as a if (0) and optimized the entire
> function out of existence.
>
> This would make the code a bit cleaner and accomplish the same.
Agreed, will try this. Thank you.
>
> -- Steve
>
>
>> }
>>
>> /**
>> @@ -3982,6 +4028,7 @@ static void __ufshcd_transfer_req_compl(struct
>> ufs_hba *hba,
>> lrbp = &hba->lrb[index];
>> cmd = lrbp->cmd;
>> if (cmd) {
>> + ufshcd_cond_add_cmd_trace(hba, index, "complete");
>> result = ufshcd_transfer_rsp_status(hba, lrbp);
>> scsi_dma_unmap(cmd);
>> cmd->result = result;
>> @@ -3993,8 +4040,11 @@ static void __ufshcd_transfer_req_compl(struct
>> ufs_hba *hba,
>> __ufshcd_release(hba);
>> } else if (lrbp->command_type == UTP_CMD_TYPE_DEV_MANAGE ||
>> lrbp->command_type == UTP_CMD_TYPE_UFS_STORAGE) {
>> - if (hba->dev_cmd.complete)
>> + if (hba->dev_cmd.complete) {
>> + ufshcd_cond_add_cmd_trace(hba, index,
>> + "dev_complete");
>> complete(hba->dev_cmd.complete);
>> + }
>> }
>> }
>>
>> diff --git a/include/trace/events/ufs.h b/include/trace/events/ufs.h
>> index 8bce504..d0ed0cf 100644
>> --- a/include/trace/events/ufs.h
>> +++ b/include/trace/events/ufs.h
>> @@ -183,6 +183,44 @@
>> TP_PROTO(const char *dev_name, int err, s64 usecs,
>> const char *dev_state, const char *link_state),
>> TP_ARGS(dev_name, err, usecs, dev_state, link_state));
>> +
>> +TRACE_EVENT(ufshcd_command,
>> + TP_PROTO(const char *dev_name, const char *str, unsigned int tag,
>> + u32 doorbell, int transfer_len, u32 intr, u64 lba,
>> + u8 opcode),
>> +
>> + TP_ARGS(dev_name, str, tag, doorbell, transfer_len, intr, lba,
>> opcode),
>> +
>> + TP_STRUCT__entry(
>> + __string(dev_name, dev_name)
>> + __string(str, str)
>> + __field(unsigned int, tag)
>> + __field(u32, doorbell)
>> + __field(int, transfer_len)
>> + __field(u32, intr)
>> + __field(u64, lba)
>> + __field(u8, opcode)
>> + ),
>> +
>> + TP_fast_assign(
>> + __assign_str(dev_name, dev_name);
>> + __assign_str(str, str);
>> + __entry->tag = tag;
>> + __entry->doorbell = doorbell;
>> + __entry->transfer_len = transfer_len;
>> + __entry->intr = intr;
>> + __entry->lba = lba;
>> + __entry->opcode = opcode;
>> + ),
>> +
>> + TP_printk(
>> + "%s: %s: tag: %u, DB: 0x%x, size: %d, IS: %u, LBA: %llu, opcode:
>> 0x%x",
>> + __get_str(str), __get_str(dev_name), __entry->tag,
>> + __entry->doorbell, __entry->transfer_len,
>> + __entry->intr, __entry->lba, (u32)__entry->opcode
>> + )
>> +);
>> +
>> #endif /* if !defined(_TRACE_UFS_H) ||
>> defined(TRACE_HEADER_MULTI_READ) */
>>
>> /* This part must be outside protection */
--
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