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From: Steven Rostedt <rostedt@goodmis.org>
To: Jeremy Linton <jeremy.linton@arm.com>
Cc: linux-kernel@vger.kernel.org, acme@redhat.com,
	namhyung@kernel.org, kapileshwar.singh@arm.com,
	scottwood@freescale.com, hekuang@huawei.com
Subject: Re: [RFC/PATCH] perf: Add sizeof operator support
Date: Fri, 17 Jun 2016 15:08:27 -0400	[thread overview]
Message-ID: <20160617150827.112f7a8d@gandalf.local.home> (raw)
In-Reply-To: <57644828.3000000@arm.com>

On Fri, 17 Jun 2016 13:57:44 -0500
Jeremy Linton <jeremy.linton@arm.com> wrote:


> That is the simple case, initially I was going to just hand code some of 
> the sizeofs in the kernel, but then I started noticing more complex 
> cases, and why I RFCed this patch.
> 
> For example, on x64/xen there are fair number with sizeof(pXXval_t), 
> IIRC I've also seen a fair number of sizeof(struct page *). Some, but I 
> dont think all of these case be determined from the field sizes like 
> this one:

Right, but there's no easy fix for that. Your patch wont fix these,
because they can change over time.

Now, what we can do is add a sizeof() helper that is like the
TRACE_DEFINE_ENUM() macro. We could add a TRACE_DEFINE_SIZEOF(), that
basically does the same, and in update_event_printk() we could
substitute the sizeof() with the actual number value.

You want to take a crack at that?

Take a look at commit 0c564a538aa93.

-- Steve


> 
> [root@X tracing]# cat events/xen/xen_mmu_set_pte/format
> name: xen_mmu_set_pte
> ID: 45
> format:
>          field:unsigned short common_type;       offset:0;       size:2; 
> signed:0;
>          field:unsigned char common_flags;       offset:2;       size:1; 
> signed:0;
>          field:unsigned char common_preempt_count;       offset:3; 
>   size:1; signed:0;
>          field:int common_pid;   offset:4;       size:4; signed:1;
> 
>          field:pte_t * ptep;     offset:8;       size:8; signed:0;
>          field:pteval_t pteval;  offset:16;      size:8; signed:0;
> 
> print fmt: "ptep %p pteval %0*llx (raw %0*llx)", REC->ptep, 
> (int)sizeof(pteval_t) * 2, (unsigned long 
> long)pte_val(native_make_pte(REC->pteval)), (int)sizeof(pteval_t) * 2, 
> (unsigned long long)REC->pteval
> 

  reply	other threads:[~2016-06-17 19:08 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-14 16:38 Jeremy Linton
2016-06-17 16:17 ` Steven Rostedt
2016-06-17 16:32   ` Jeremy Linton
2016-06-17 16:50     ` Steven Rostedt
2016-06-17 18:57       ` Jeremy Linton
2016-06-17 19:08         ` Steven Rostedt [this message]
2016-06-20  0:29           ` Namhyung Kim
2017-04-30 22:06 ` Jon Masters
2017-05-02 11:47   ` Jeremy Linton

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