<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-toradex.git/arch/arc/include/asm/cacheflush.h, branch v4.1-rc4</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>ARC: [mm] Assume pagecache page dirty by default</title>
<updated>2013-06-22T13:53:19+00:00</updated>
<author>
<name>Vineet Gupta</name>
<email>vgupta@synopsys.com</email>
</author>
<published>2013-05-13T11:53:58+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=2ed21dae021db1f9f988494ceee519290217520d'/>
<id>2ed21dae021db1f9f988494ceee519290217520d</id>
<content type='text'>
Similar to ARM/SH

Signed-off-by: Vineet Gupta &lt;vgupta@synopsys.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Similar to ARM/SH

Signed-off-by: Vineet Gupta &lt;vgupta@synopsys.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ARC: cache detection code bitrot</title>
<updated>2013-06-22T08:16:43+00:00</updated>
<author>
<name>Vineet Gupta</name>
<email>vgupta@synopsys.com</email>
</author>
<published>2013-06-15T04:51:51+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=30499186602afa1d62c2e5d354d02214a0ee00b7'/>
<id>30499186602afa1d62c2e5d354d02214a0ee00b7</id>
<content type='text'>
* Number of (i|d)cache ways can be retrieved from BCRs and hence no need
  to cross check with with built-in constants
* Use of IS_ENABLED() to check for a Kconfig option
* is_not_cache_aligned() not used anymore

Signed-off-by: Vineet Gupta &lt;vgupta@synopsys.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
* Number of (i|d)cache ways can be retrieved from BCRs and hence no need
  to cross check with with built-in constants
* Use of IS_ENABLED() to check for a Kconfig option
* is_not_cache_aligned() not used anymore

Signed-off-by: Vineet Gupta &lt;vgupta@synopsys.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ARC: Use enough bits for determining page's cache color</title>
<updated>2013-05-23T08:55:09+00:00</updated>
<author>
<name>Vineet Gupta</name>
<email>vgupta@synopsys.com</email>
</author>
<published>2013-05-19T08:36:44+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=006dfb3c9c44192f06093d65b3a876fa5ad1319a'/>
<id>006dfb3c9c44192f06093d65b3a876fa5ad1319a</id>
<content type='text'>
The current code uses 2 bits for determining page's dcache color, thus
sorting pages into 4 bins, whereas the aliasing dcache really has 2 bins
(8k page, 64k dcache - 4 way-set-assoc).
This can cause extraneous flushes - e.g. color 0 and 2.

Signed-off-by: Vineet Gupta &lt;vgupta@synopsys.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The current code uses 2 bits for determining page's dcache color, thus
sorting pages into 4 bins, whereas the aliasing dcache really has 2 bins
(8k page, 64k dcache - 4 way-set-assoc).
This can cause extraneous flushes - e.g. color 0 and 2.

Signed-off-by: Vineet Gupta &lt;vgupta@synopsys.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ARC: Brown paper bag bug in macro for checking cache color</title>
<updated>2013-05-23T08:54:52+00:00</updated>
<author>
<name>Vineet Gupta</name>
<email>vgupta@synopsys.com</email>
</author>
<published>2013-05-22T13:08:10+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=3e87974dec5ec25a8a4852d9292db6be659164e6'/>
<id>3e87974dec5ec25a8a4852d9292db6be659164e6</id>
<content type='text'>
The VM_EXEC check in update_mmu_cache() was getting optimized away
because of a stupid error in definition of macro addr_not_cache_congruent()

The intention was to have the equivalent of following:

	if (a || (1 ? b : 0))

but we ended up with following:

	if (a || 1 ? b : 0)

And because precedence of '||' is more that that of '?', gcc was optimizing
away evaluation of &lt;a&gt;

Nasty Repercussions:
1. For non-aliasing configs it would mean some extraneous dcache flushes
   for non-code pages if U/K mappings were not congruent.
2. For aliasing config, some needed dcache flush for code pages might
   be missed if U/K mappings were congruent.

Signed-off-by: Vineet Gupta &lt;vgupta@synopsys.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The VM_EXEC check in update_mmu_cache() was getting optimized away
because of a stupid error in definition of macro addr_not_cache_congruent()

The intention was to have the equivalent of following:

	if (a || (1 ? b : 0))

but we ended up with following:

	if (a || 1 ? b : 0)

And because precedence of '||' is more that that of '?', gcc was optimizing
away evaluation of &lt;a&gt;

Nasty Repercussions:
1. For non-aliasing configs it would mean some extraneous dcache flushes
   for non-code pages if U/K mappings were not congruent.
2. For aliasing config, some needed dcache flush for code pages might
   be missed if U/K mappings were congruent.

Signed-off-by: Vineet Gupta &lt;vgupta@synopsys.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ARC: [mm] Aliasing VIPT dcache support 4/4</title>
<updated>2013-05-09T16:30:57+00:00</updated>
<author>
<name>Vineet Gupta</name>
<email>vgupta@synopsys.com</email>
</author>
<published>2013-05-09T13:50:43+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=5bba49f5397c012d873c73860ad7b50c526e613b'/>
<id>5bba49f5397c012d873c73860ad7b50c526e613b</id>
<content type='text'>
Enforce congruency of userspace shared mappings

Signed-off-by: Vineet Gupta &lt;vgupta@synopsys.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Enforce congruency of userspace shared mappings

Signed-off-by: Vineet Gupta &lt;vgupta@synopsys.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ARC: [mm] Aliasing VIPT dcache support 3/4</title>
<updated>2013-05-09T16:30:57+00:00</updated>
<author>
<name>Vineet Gupta</name>
<email>vgupta@synopsys.com</email>
</author>
<published>2013-05-09T16:25:27+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=de2a852cc0d4c4d6a9c22a597c9cc231f2e6ceb4'/>
<id>de2a852cc0d4c4d6a9c22a597c9cc231f2e6ceb4</id>
<content type='text'>
Fix the one zillion warnings

Signed-off-by: Vineet Gupta &lt;vgupta@synopsys.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Fix the one zillion warnings

Signed-off-by: Vineet Gupta &lt;vgupta@synopsys.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ARC: [mm] Aliasing VIPT dcache support 2/4</title>
<updated>2013-05-09T16:29:46+00:00</updated>
<author>
<name>Vineet Gupta</name>
<email>vgupta@synopsys.com</email>
</author>
<published>2013-05-09T16:24:51+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=4102b53392d6397d80b6e09b516517efacf7ea77'/>
<id>4102b53392d6397d80b6e09b516517efacf7ea77</id>
<content type='text'>
This is the meat of the series which prevents any dcache alias creation
by always keeping the U and K mapping of a page congruent.
If a mapping already exists, and other tries to access the page, prev
one is flushed to physical page (wback+inv)

Essentially flush_dcache_page()/copy_user_highpage() create K-mapping
of a page, but try to defer flushing, unless U-mapping exist.
When page is actually mapped to userspace, update_mmu_cache() flushes
the K-mapping (in certain cases this can be optimised out)

Additonally flush_cache_mm(), flush_cache_range(), flush_cache_page()
handle the puring of stale userspace mappings on exit/munmap...

flush_anon_page() handles the existing U-mapping for anon page before
kernel reads it via the GUP path.

Note that while not complete, this is enough to boot a simple
dynamically linked Busybox based rootfs

Signed-off-by: Vineet Gupta &lt;vgupta@synopsys.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This is the meat of the series which prevents any dcache alias creation
by always keeping the U and K mapping of a page congruent.
If a mapping already exists, and other tries to access the page, prev
one is flushed to physical page (wback+inv)

Essentially flush_dcache_page()/copy_user_highpage() create K-mapping
of a page, but try to defer flushing, unless U-mapping exist.
When page is actually mapped to userspace, update_mmu_cache() flushes
the K-mapping (in certain cases this can be optimised out)

Additonally flush_cache_mm(), flush_cache_range(), flush_cache_page()
handle the puring of stale userspace mappings on exit/munmap...

flush_anon_page() handles the existing U-mapping for anon page before
kernel reads it via the GUP path.

Note that while not complete, this is enough to boot a simple
dynamically linked Busybox based rootfs

Signed-off-by: Vineet Gupta &lt;vgupta@synopsys.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ARC: [mm] Aliasing VIPT dcache support 1/4</title>
<updated>2013-05-09T16:23:16+00:00</updated>
<author>
<name>Vineet Gupta</name>
<email>vgupta@synopsys.com</email>
</author>
<published>2013-05-09T09:40:18+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=6ec18a81b22ab2b40df8424f2b5fc6be20ccad87'/>
<id>6ec18a81b22ab2b40df8424f2b5fc6be20ccad87</id>
<content type='text'>
This preps the low level dcache flush helpers to take vaddr argument in
addition to the existing paddr to properly flush the VIPT dcache

Signed-off-by: Vineet Gupta &lt;vgupta@synopsys.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This preps the low level dcache flush helpers to take vaddr argument in
addition to the existing paddr to properly flush the VIPT dcache

Signed-off-by: Vineet Gupta &lt;vgupta@synopsys.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ARC: [mm] Lazy D-cache flush (non aliasing VIPT)</title>
<updated>2013-05-07T13:38:15+00:00</updated>
<author>
<name>Vineet Gupta</name>
<email>vgupta@synopsys.com</email>
</author>
<published>2013-04-16T08:40:48+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=eacd0e950dc2100af54f2a94ae29105bf48ab921'/>
<id>eacd0e950dc2100af54f2a94ae29105bf48ab921</id>
<content type='text'>
flush_dcache_page( ) is MM hook to ensure that a page has consistent
views between kernel and userspace. Thus it is called when

* kernel writes to a page which at some later point could get mapped to
  userspace (so kernel mapping needs to be flushed-n-inv)
* kernel is about to read from a page with possible userspace mappings
  (so userspace mappings needs to be made coherent with kernel ones)

However for Non aliasing VIPT dcache, any userspace mapping will always
be congruent to kernel mapping. Thus d-cache need need not be flushed at
all (or delayed indefinitely).

The only reason it does need to be flushed is when mapping code pages.
Since icache doesn't snoop dcache, those dirty dcache lines need to be
written back to memory and icache line invalidated so that icache lines
fetch will get the right data.

Decent gains on LMBench fork/exec/sh and File I/O micro-benchmarks.

(1) FPGA @ 80 MHZ

Processor, Processes - times in microseconds - smaller is better
------------------------------------------------------------------------------
Host                 OS  Mhz null null      open slct sig  sig  fork exec sh
                             call  I/O stat clos TCP  inst hndl proc proc proc
--------- ------------- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ----
3.9-rc6-a Linux 3.9.0-r   80 4.79 8.72 66.7 116. 239. 8.39 30.4 4798 14.K 34.K
3.9-rc6-b Linux 3.9.0-r   80 4.79 8.62 65.4 111. 239. 8.35 29.0 3995 12.K 30.K
3.9-rc7-c Linux 3.9.0-r   80 4.79 9.00 66.1 106. 239. 8.61 30.4 2858 10.K 24.K
                                                                ^^^^ ^^^^ ^^^

File &amp; VM system latencies in microseconds - smaller is better
-------------------------------------------------------------------------------
Host                 OS   0K File      10K File     Mmap    Prot   Page 100fd
                        Create Delete Create Delete Latency Fault  Fault selct
--------- ------------- ------ ------ ------ ------ ------- ----- ------- -----
3.9-rc6-a Linux 3.9.0-r  317.8  204.2 1122.3  375.1 3522.0 4.288     20.7 126.8
3.9-rc6-b Linux 3.9.0-r  298.7  223.0 1141.6  367.8 3531.0 4.866     20.9 126.4
3.9-rc7-c Linux 3.9.0-r  278.4  179.2  862.1  339.3 3705.0 3.223     20.3 126.6
                         ^^^^^  ^^^^^  ^^^^^  ^^^^

(2) Customer Silicon @ 500 MHz (166 MHz mem)

------------------------------------------------------------------------------
Host                 OS  Mhz null null      open slct sig  sig  fork exec sh
                             call  I/O stat clos TCP  inst hndl proc proc proc
--------- ------------- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ----
abilis-ba Linux 3.9.0-r  497 0.71 1.38 4.58 12.0 35.5 1.40 3.89 2070 5525 13.K
abilis-ca Linux 3.9.0-r  497 0.71 1.40 4.61 11.8 35.6 1.37 3.92 1411 4317 10.K
                                                                ^^^^ ^^^^ ^^^

Signed-off-by: Vineet Gupta &lt;vgupta@synopsys.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
flush_dcache_page( ) is MM hook to ensure that a page has consistent
views between kernel and userspace. Thus it is called when

* kernel writes to a page which at some later point could get mapped to
  userspace (so kernel mapping needs to be flushed-n-inv)
* kernel is about to read from a page with possible userspace mappings
  (so userspace mappings needs to be made coherent with kernel ones)

However for Non aliasing VIPT dcache, any userspace mapping will always
be congruent to kernel mapping. Thus d-cache need need not be flushed at
all (or delayed indefinitely).

The only reason it does need to be flushed is when mapping code pages.
Since icache doesn't snoop dcache, those dirty dcache lines need to be
written back to memory and icache line invalidated so that icache lines
fetch will get the right data.

Decent gains on LMBench fork/exec/sh and File I/O micro-benchmarks.

(1) FPGA @ 80 MHZ

Processor, Processes - times in microseconds - smaller is better
------------------------------------------------------------------------------
Host                 OS  Mhz null null      open slct sig  sig  fork exec sh
                             call  I/O stat clos TCP  inst hndl proc proc proc
--------- ------------- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ----
3.9-rc6-a Linux 3.9.0-r   80 4.79 8.72 66.7 116. 239. 8.39 30.4 4798 14.K 34.K
3.9-rc6-b Linux 3.9.0-r   80 4.79 8.62 65.4 111. 239. 8.35 29.0 3995 12.K 30.K
3.9-rc7-c Linux 3.9.0-r   80 4.79 9.00 66.1 106. 239. 8.61 30.4 2858 10.K 24.K
                                                                ^^^^ ^^^^ ^^^

File &amp; VM system latencies in microseconds - smaller is better
-------------------------------------------------------------------------------
Host                 OS   0K File      10K File     Mmap    Prot   Page 100fd
                        Create Delete Create Delete Latency Fault  Fault selct
--------- ------------- ------ ------ ------ ------ ------- ----- ------- -----
3.9-rc6-a Linux 3.9.0-r  317.8  204.2 1122.3  375.1 3522.0 4.288     20.7 126.8
3.9-rc6-b Linux 3.9.0-r  298.7  223.0 1141.6  367.8 3531.0 4.866     20.9 126.4
3.9-rc7-c Linux 3.9.0-r  278.4  179.2  862.1  339.3 3705.0 3.223     20.3 126.6
                         ^^^^^  ^^^^^  ^^^^^  ^^^^

(2) Customer Silicon @ 500 MHz (166 MHz mem)

------------------------------------------------------------------------------
Host                 OS  Mhz null null      open slct sig  sig  fork exec sh
                             call  I/O stat clos TCP  inst hndl proc proc proc
--------- ------------- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ----
abilis-ba Linux 3.9.0-r  497 0.71 1.38 4.58 12.0 35.5 1.40 3.89 2070 5525 13.K
abilis-ca Linux 3.9.0-r  497 0.71 1.40 4.61 11.8 35.6 1.37 3.92 1411 4317 10.K
                                                                ^^^^ ^^^^ ^^^

Signed-off-by: Vineet Gupta &lt;vgupta@synopsys.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ARC: [mm] consolidate icache/dcache sync code</title>
<updated>2013-05-07T13:38:13+00:00</updated>
<author>
<name>Vineet Gupta</name>
<email>vgupta@synopsys.com</email>
</author>
<published>2013-04-12T06:50:23+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=94bad1afeeefbd1b27d7f642de12c04339501a99'/>
<id>94bad1afeeefbd1b27d7f642de12c04339501a99</id>
<content type='text'>
Now that we have same helper used for all icache invalidates (i.e.
vaddr+paddr based exact line invalidate), consolidate the open coded
calls into one place.

Also rename flush_icache_range_vaddr =&gt; __sync_icache_dcache

Signed-off-by: Vineet Gupta &lt;vgupta@synopsys.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Now that we have same helper used for all icache invalidates (i.e.
vaddr+paddr based exact line invalidate), consolidate the open coded
calls into one place.

Also rename flush_icache_range_vaddr =&gt; __sync_icache_dcache

Signed-off-by: Vineet Gupta &lt;vgupta@synopsys.com&gt;
</pre>
</div>
</content>
</entry>
</feed>
