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Restore mysteriously lost portion of PCID report, add URL to repository

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Warren Block 2015-07-19 19:27:26 +00:00
parent 2381913cab
commit aa81505573
Notes: svn2git 2020-12-08 03:00:23 +00:00 
svn path=/head/; revision=47018
1 changed files with 26 additions and 0 deletions
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en_US.ISO8859-1/htdocs/news/status/report-2015-04-2015-06.xml
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@ -1085,6 +1085,11 @@
</person>
</contact>
<links>
<url href="https://svnweb.freebsd.org/base?view=revision&amp;revision=282684">Commit
r282684</url>
</links>
<body>
<p>Process-Context Identifiers (PCIDs) is a feature of the
Translation Lookaside Buffer (TLB) on Intel processors,
@ -1128,7 +1133,28 @@
performed. As result, the new implementation issues exactly
the same amount of shootdown IPIs as pmap which does not
utilize PCID.</p>
<p>Another change included with the PCID rewrite is a move of
the address space switching code from assembler to C source,
making the algorithm easier to understand and validate.</p>
<p>Measurements done with <tt>hwpmc(4)</tt> on a Haswell machine
indicated that the new implementation reduced the amount of
data TLB misses up to 10 times, without an impact on the IPI
counters.</p>
<p>The rewrite was committed to HEAD at r282684.</p>
<p>Note: AMD processors do not have PCID feature for host paging
(AMD provides ASIDs for SVM use). But it is likely that AMD
processors do cache TLB translations for different address
spaces transparently, and snoop writes to the page tables to
invalidate the caches.</p>
</body>
<sponsor>
The FreeBSD Foundation
</sponsor>
</project>
<project cat='proj'>