From: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
To: Masami Hiramatsu <mhiramat@kernel.org>
Cc: oleg@redhat.com, peterz@infradead.org, srikar@linux.vnet.ibm.com,
acme@kernel.org, ananth@linux.vnet.ibm.com,
akpm@linux-foundation.org, alexander.shishkin@linux.intel.com,
alexis.berlemont@gmail.com, corbet@lwn.net,
dan.j.williams@intel.com, gregkh@linuxfoundation.org,
huawei.libin@huawei.com, hughd@google.com, jack@suse.cz,
jglisse@redhat.com, jolsa@redhat.com, kan.liang@intel.com,
kirill.shutemov@linux.intel.com, kjlx@templeofstupid.com,
kstewart@linuxfoundation.org, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
mhocko@suse.com, milian.wolff@kdab.com, mingo@redhat.com,
namhyung@kernel.org, naveen.n.rao@linux.vnet.ibm.com,
pc@us.ibm.com, pombredanne@nexb.com, rostedt@goodmis.org,
tglx@linutronix.de, tmricht@linux.vnet.ibm.com,
willy@infradead.org, yao.jin@linux.intel.com,
fengguang.wu@intel.com,
Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Subject: Re: [PATCH 5/8] trace_uprobe: Support SDT markers having reference count (semaphore)
Date: Wed, 14 Mar 2018 20:42:24 +0530 [thread overview]
Message-ID: <fabfad9d-a75e-0b18-1558-ce738b46e538@linux.vnet.ibm.com> (raw)
In-Reply-To: <20180314224809.5ee4c8834bb366faa398e342@kernel.org>
Hi Masami,
On 03/14/2018 07:18 PM, Masami Hiramatsu wrote:
> Hi Ravi,
>
> On Tue, 13 Mar 2018 18:26:00 +0530
> Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com> wrote:
>
>> Userspace Statically Defined Tracepoints[1] are dtrace style markers
>> inside userspace applications. These markers are added by developer at
>> important places in the code. Each marker source expands to a single
>> nop instruction in the compiled code but there may be additional
>> overhead for computing the marker arguments which expands to couple of
>> instructions. In case the overhead is more, execution of it can be
>> ommited by runtime if() condition when no one is tracing on the marker:
>>
>> if (reference_counter > 0) {
>> Execute marker instructions;
>> }
>>
>> Default value of reference counter is 0. Tracer has to increment the
>> reference counter before tracing on a marker and decrement it when
>> done with the tracing.
>>
>> Implement the reference counter logic in trace_uprobe, leaving core
>> uprobe infrastructure as is, except one new callback from uprobe_mmap()
>> to trace_uprobe.
>>
>> trace_uprobe definition with reference counter will now be:
>>
>> <path>:<offset>[(ref_ctr_offset)]
> Would you mean
> <path>:<offset>(<ref_ctr_offset>)
> ?
>
> or use "[]" for delimiter?
[] indicates optional field.
> Since,
>
>> @@ -454,6 +458,26 @@ static int create_trace_uprobe(int argc, char **argv)
>> goto fail_address_parse;
>> }
>>
>> + /* Parse reference counter offset if specified. */
>> + rctr = strchr(arg, '(');
> This seems you choose "()" for delimiter.
Correct.
>> + if (rctr) {
>> + rctr_end = strchr(arg, ')');
> rctr_end = strchr(rctr, ')');
>
> ? since we are sure rctr != NULL.
Yes. we can use rctr instead of arg.
>> + if (rctr > rctr_end || *(rctr_end + 1) != 0) {
>> + ret = -EINVAL;
>> + pr_info("Invalid reference counter offset.\n");
>> + goto fail_address_parse;
>> + }
>
> Also
>
>> +
>> + *rctr++ = 0;
>> + *rctr_end = 0;
> Please consider to use '\0' for nul;
Sure. Will change it.
Thanks for the review :)
Ravi
next prev parent reply other threads:[~2018-03-14 15:12 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-13 12:55 [PATCH 0/8] trace_uprobe: Support SDT markers having reference count (semaphore) Ravi Bangoria
2018-03-13 12:55 ` [PATCH 1/8] Uprobe: Export vaddr <-> offset conversion functions Ravi Bangoria
2018-03-13 20:36 ` Jerome Glisse
2018-03-15 16:27 ` Steven Rostedt
2018-03-16 8:54 ` Ravi Bangoria
2018-03-13 12:55 ` [PATCH 2/8] mm: Prefix vma_ to vaddr_to_offset() and offset_to_vaddr() Ravi Bangoria
2018-03-13 20:38 ` Jerome Glisse
2018-03-15 16:28 ` Steven Rostedt
2018-03-16 8:58 ` Ravi Bangoria
2018-03-13 12:55 ` [PATCH 3/8] Uprobe: Rename map_info to uprobe_map_info Ravi Bangoria
2018-03-13 20:39 ` Jerome Glisse
2018-03-15 16:44 ` Steven Rostedt
2018-03-16 8:56 ` Ravi Bangoria
2018-03-13 12:55 ` [PATCH 4/8] Uprobe: Export uprobe_map_info along with uprobe_{build/free}_map_info() Ravi Bangoria
2018-03-13 20:40 ` Jerome Glisse
2018-03-15 16:32 ` Steven Rostedt
2018-03-16 8:59 ` Ravi Bangoria
2018-03-13 12:56 ` [PATCH 5/8] trace_uprobe: Support SDT markers having reference count (semaphore) Ravi Bangoria
2018-03-14 13:48 ` Masami Hiramatsu
2018-03-14 15:12 ` Ravi Bangoria [this message]
2018-03-14 16:59 ` Oleg Nesterov
2018-03-15 11:23 ` Ravi Bangoria
2018-03-19 4:28 ` Ravi Bangoria
2018-03-19 13:46 ` Oleg Nesterov
2018-03-14 21:58 ` Steven Rostedt
2018-03-15 14:21 ` Oleg Nesterov
2018-03-15 14:30 ` Oleg Nesterov
2018-03-16 9:28 ` Ravi Bangoria
2018-03-16 11:39 ` Oleg Nesterov
2018-03-16 11:46 ` Ravi Bangoria
2018-03-16 9:21 ` Ravi Bangoria
2018-03-15 15:01 ` Oleg Nesterov
2018-03-16 9:31 ` Ravi Bangoria
2018-03-15 16:48 ` Steven Rostedt
2018-03-16 9:01 ` Ravi Bangoria
2018-03-16 16:16 ` Oleg Nesterov
2018-03-13 12:56 ` [PATCH 6/8] trace_uprobe/sdt: Fix multiple update of same reference counter Ravi Bangoria
2018-03-14 14:15 ` Masami Hiramatsu
2018-03-14 15:15 ` Ravi Bangoria
2018-03-15 14:49 ` Oleg Nesterov
2018-03-16 12:12 ` Ravi Bangoria
2018-03-16 13:49 ` Ravi Bangoria
2018-03-16 17:50 ` Oleg Nesterov
2018-03-19 9:18 ` Ravi Bangoria
2018-03-19 13:40 ` Oleg Nesterov
2018-03-13 12:56 ` [PATCH 7/8] perf probe: Support SDT markers having reference counter (semaphore) Ravi Bangoria
2018-03-14 14:09 ` Masami Hiramatsu
2018-03-14 15:21 ` Ravi Bangoria
2018-03-13 12:56 ` [PATCH 8/8] trace_uprobe/sdt: Document about reference counter Ravi Bangoria
2018-03-14 13:50 ` Masami Hiramatsu
2018-03-14 15:22 ` Ravi Bangoria
2018-03-15 12:47 ` Masami Hiramatsu
2018-03-16 9:42 ` Ravi Bangoria
2018-03-16 14:26 ` Masami Hiramatsu
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