From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
To: Wilco Dijkstra <Wilco.Dijkstra@arm.com>
Cc: Wilco Dijkstra via Libc-alpha <libc-alpha@sourceware.org>
Subject: Re: [PATCH] AArch64: Add hp-timing.h
Date: Mon, 28 Jun 2021 11:46:59 -0300 [thread overview]
Message-ID: <70c5dbe8-3e6c-5831-6f79-550e15356074@linaro.org> (raw)
In-Reply-To: <VE1PR08MB55998C3455D8FD3B445C210583039@VE1PR08MB5599.eurprd08.prod.outlook.com>
On 28/06/2021 11:24, Wilco Dijkstra wrote:
> Hi Adhemerval,
>
>> Any particular reason why you haven't enabled HP_TIMING_INLINE to 1?
>
> Well, what exactly is it used for? I've never quite understood the reasoning behind
> hp-timing. It seems to me it just slows down ld.so with extra timing calls which are
> unused 100% of the time. So I don't see a reason to enable it on AArch64. However
> with the header in place, it's easy to set it to 1 and rebuild if needed.
It is used for LD_DEBUG=statistics to give better profiling numbers
(theoretically). However, the profiling is still measured in some
parts even LD_DEBUG is not set unfortunately. It assumes that reading
the clock is as fast as one instructions, that why it is only enabled
for HP_TIMING_INLINE.
Not sure if it is worth to enable on aarch64 indeed.
next prev parent reply other threads:[~2021-06-28 14:47 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-28 10:11 Wilco Dijkstra
2021-06-28 10:20 ` Florian Weimer
2021-06-28 10:53 ` Wilco Dijkstra
2021-06-28 11:06 ` Florian Weimer
2021-06-28 11:35 ` Wilco Dijkstra
2021-06-28 11:39 ` Florian Weimer
2021-06-28 11:49 ` Szabolcs Nagy
2021-06-28 11:55 ` Adhemerval Zanella
2021-06-28 12:10 ` Wilco Dijkstra
2021-06-28 13:15 ` Adhemerval Zanella
2021-06-28 14:24 ` Wilco Dijkstra
2021-06-28 14:46 ` Adhemerval Zanella [this message]
2021-06-28 19:16 ` Wilco Dijkstra
2021-06-30 8:46 ` Szabolcs Nagy
2021-06-30 8:55 ` Florian Weimer
2021-06-30 9:33 ` Siddhesh Poyarekar
2021-07-01 10:21 ` Wilco Dijkstra
2021-07-01 13:48 ` Szabolcs Nagy
2021-07-01 15:33 ` Wilco Dijkstra
2021-07-06 11:33 ` Florian Weimer
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