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<title>linux-toradex.git/arch/x86/lib/delay.c, branch v3.2</title>
<subtitle>Linux kernel for Apalis and Colibri modules</subtitle>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/'/>
<entry>
<title>x86: udelay: Use this_cpu_read to avoid address calculation</title>
<updated>2011-01-04T05:08:55+00:00</updated>
<author>
<name>Christoph Lameter</name>
<email>cl@linux.com</email>
</author>
<published>2010-12-16T18:14:43+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=357089fca91f639dd005ae0721f5f932b4f276ab'/>
<id>357089fca91f639dd005ae0721f5f932b4f276ab</id>
<content type='text'>
The code will use a segment prefix instead of doing the lookup and
calculation.

Signed-off-by: Christoph Lameter &lt;cl@linux.com&gt;
Acked-by: "H. Peter Anvin" &lt;hpa@zytor.com&gt;
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
</content>
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<pre>
The code will use a segment prefix instead of doing the lookup and
calculation.

Signed-off-by: Christoph Lameter &lt;cl@linux.com&gt;
Acked-by: "H. Peter Anvin" &lt;hpa@zytor.com&gt;
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>x86, delay: tsc based udelay should have rdtsc_barrier</title>
<updated>2009-06-25T23:47:40+00:00</updated>
<author>
<name>Pallipadi, Venkatesh</name>
<email>venkatesh.pallipadi@intel.com</email>
</author>
<published>2009-06-25T23:44:31+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=e888d7facd1f1460a638151036d15b6cfb3ccc74'/>
<id>e888d7facd1f1460a638151036d15b6cfb3ccc74</id>
<content type='text'>
delay_tsc needs rdtsc_barrier to provide proper delay.

Output from a test driver using hpet to cross check delay
provided by udelay().

Before:
[   86.794363] Expected delay 5us actual 4679ns
[   87.154362] Expected delay 5us actual 698ns
[   87.514162] Expected delay 5us actual 4539ns
[   88.653716] Expected delay 5us actual 4539ns
[   94.664106] Expected delay 10us actual 9638ns
[   95.049351] Expected delay 10us actual 10126ns
[   95.416110] Expected delay 10us actual 9568ns
[   95.799216] Expected delay 10us actual 9638ns
[  103.624104] Expected delay 10us actual 9707ns
[  104.020619] Expected delay 10us actual 768ns
[  104.419951] Expected delay 10us actual 9707ns

After:
[   50.983320] Expected delay 5us actual 5587ns
[   51.261807] Expected delay 5us actual 5587ns
[   51.565715] Expected delay 5us actual 5657ns
[   51.861171] Expected delay 5us actual 5587ns
[   52.164704] Expected delay 5us actual 5726ns
[   52.487457] Expected delay 5us actual 5657ns
[   52.789338] Expected delay 5us actual 5726ns
[   57.119680] Expected delay 10us actual 10755ns
[   57.893997] Expected delay 10us actual 10615ns
[   58.261287] Expected delay 10us actual 10755ns
[   58.620505] Expected delay 10us actual 10825ns
[   58.941035] Expected delay 10us actual 10755ns
[   59.320903] Expected delay 10us actual 10615ns
[   61.306311] Expected delay 10us actual 10755ns
[   61.520542] Expected delay 10us actual 10615ns

Signed-off-by: Venkatesh Pallipadi &lt;venkatesh.pallipadi@intel.com&gt;
Signed-off-by: H. Peter Anvin &lt;hpa@zytor.com&gt;
</content>
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<pre>
delay_tsc needs rdtsc_barrier to provide proper delay.

Output from a test driver using hpet to cross check delay
provided by udelay().

Before:
[   86.794363] Expected delay 5us actual 4679ns
[   87.154362] Expected delay 5us actual 698ns
[   87.514162] Expected delay 5us actual 4539ns
[   88.653716] Expected delay 5us actual 4539ns
[   94.664106] Expected delay 10us actual 9638ns
[   95.049351] Expected delay 10us actual 10126ns
[   95.416110] Expected delay 10us actual 9568ns
[   95.799216] Expected delay 10us actual 9638ns
[  103.624104] Expected delay 10us actual 9707ns
[  104.020619] Expected delay 10us actual 768ns
[  104.419951] Expected delay 10us actual 9707ns

After:
[   50.983320] Expected delay 5us actual 5587ns
[   51.261807] Expected delay 5us actual 5587ns
[   51.565715] Expected delay 5us actual 5657ns
[   51.861171] Expected delay 5us actual 5587ns
[   52.164704] Expected delay 5us actual 5726ns
[   52.487457] Expected delay 5us actual 5657ns
[   52.789338] Expected delay 5us actual 5726ns
[   57.119680] Expected delay 10us actual 10755ns
[   57.893997] Expected delay 10us actual 10615ns
[   58.261287] Expected delay 10us actual 10755ns
[   58.620505] Expected delay 10us actual 10825ns
[   58.941035] Expected delay 10us actual 10755ns
[   59.320903] Expected delay 10us actual 10615ns
[   61.306311] Expected delay 10us actual 10755ns
[   61.520542] Expected delay 10us actual 10615ns

Signed-off-by: Venkatesh Pallipadi &lt;venkatesh.pallipadi@intel.com&gt;
Signed-off-by: H. Peter Anvin &lt;hpa@zytor.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>x86: integrate delay functions.</title>
<updated>2008-07-09T06:52:05+00:00</updated>
<author>
<name>Glauber Costa</name>
<email>gcosta@redhat.com</email>
</author>
<published>2008-07-03T15:35:41+00:00</published>
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<id>f0fbf0abc093ec8bf64506eee4ede9e5daf40ffd</id>
<content type='text'>
delay_32.c, delay_64.c are now equal, and are integrated into delay.c.

Signed-off-by: Glauber Costa &lt;gcosta@redhat.com&gt;
Signed-off-by: H. Peter Anvin &lt;hpa@zytor.com&gt;
Signed-off-by: Ingo Molnar &lt;mingo@elte.hu&gt;
</content>
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<pre>
delay_32.c, delay_64.c are now equal, and are integrated into delay.c.

Signed-off-by: Glauber Costa &lt;gcosta@redhat.com&gt;
Signed-off-by: H. Peter Anvin &lt;hpa@zytor.com&gt;
Signed-off-by: Ingo Molnar &lt;mingo@elte.hu&gt;
</pre>
</div>
</content>
</entry>
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