From: Thomas Huth <thuth@redhat.com>
To: Pierre Morel <pmorel@linux.ibm.com>,
Janosch Frank <frankja@linux.ibm.com>,
kvm@vger.kernel.org
Cc: linux-s390@vger.kernel.org, david@redhat.com
Subject: Re: [PATCH v1 4/4] s390x: Testing the Subchannel I/O read
Date: Thu, 14 Nov 2019 17:51:09 +0100 [thread overview]
Message-ID: <75b72389-eec5-200f-01af-512d1294f137@redhat.com> (raw)
In-Reply-To: <81ef68d4-5ec5-b14e-6c3d-6935e9a6a1c1@linux.ibm.com>
On 14/11/2019 17.38, Pierre Morel wrote:
[...]
>>> +static char buffer[4096];
>>> +
>>> +static void delay(int d)
>>> +{
>>> + int i, j;
>>> +
>>> + while (d--)
>>> + for (i = 1000000; i; i--)
>>> + for (j = 1000000; j; j--)
>>> + ;
>>> +}
>> You could set a timer.
>
> Hum, do we really want to do this?
I'm pretty sure that the compiler optimizes empty loops away. Maybe have
a look at the disassembly of your delay function...
Anyway, it's likely better to use STCK and friends to get a proper
timing. You could move get_clock_ms() from s390x/intercept.c to the
lib/s390x folder and then use that function here.
Thomas
next prev parent reply other threads:[~2019-11-14 16:51 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-13 12:23 [PATCH v1 0/4] s390x: Testing the Subchannel I/O Pierre Morel
2019-11-13 12:23 ` [PATCH v1 1/4] s390x: saving regs for interrupts Pierre Morel
2019-11-13 16:12 ` Janosch Frank
2019-11-14 10:11 ` Pierre Morel
2019-11-14 10:28 ` David Hildenbrand
2019-11-14 11:57 ` Pierre Morel
2019-11-14 12:11 ` David Hildenbrand
2019-11-14 15:21 ` Pierre Morel
2019-11-14 15:25 ` David Hildenbrand
2019-11-14 16:15 ` Pierre Morel
2019-11-13 12:23 ` [PATCH v1 2/4] s390x: Define the PSW bits Pierre Morel
2019-11-13 16:05 ` Janosch Frank
2019-11-14 8:40 ` Pierre Morel
2019-11-14 8:53 ` Janosch Frank
2019-11-14 15:25 ` Pierre Morel
2019-11-13 12:23 ` [PATCH v1 3/4] s390x:irq: make IRQ handler weak Pierre Morel
2019-11-15 7:12 ` Thomas Huth
2019-11-18 9:04 ` Pierre Morel
2019-11-13 12:23 ` [PATCH v1 4/4] s390x: Testing the Subchannel I/O read Pierre Morel
2019-11-13 13:05 ` Cornelia Huck
2019-11-14 10:11 ` Pierre Morel
2019-11-21 16:02 ` Cornelia Huck
2019-11-22 9:03 ` Pierre Morel
2019-11-22 10:54 ` Cornelia Huck
2019-11-22 12:48 ` Pierre Morel
2019-11-14 9:15 ` Janosch Frank
2019-11-14 16:38 ` Pierre Morel
2019-11-14 16:51 ` Thomas Huth [this message]
2019-11-14 17:50 ` Pierre Morel
2019-11-14 17:09 ` Janosch Frank
2019-11-14 17:55 ` Pierre Morel
2019-11-13 12:35 ` [PATCH v1 0/4] s390x: Testing the Subchannel I/O Thomas Huth
2019-11-13 12:43 ` Pierre Morel
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