retention flop & low power design

http://www.globalspec.com/reference/68027/203279/chapter-13-retention-register-design

http://vlsi-soc.blogspot.com/2013/03/state-retention-power-gating.html

http://www.soccentral.com/results.asp?EntryID=27642

http://blogs.synopsys.com/magicbluesmoke/2007/04/15/special-cells-required-for-multi-voltage-design/

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并发问题中活锁(live lock)到底指的是什么?

活锁和死锁在表现上是一样的两个线程都没有任何进展,
但是区别在于:
死锁,两个线程都处于阻塞状态,
而活锁呢,并不会阻塞,而是一直尝试去获取需要的锁,不断的try,这种情况下线程并没有阻塞所以是活的状态,但是只是在做无用功。
对应Wikipedia的例子的话,两个人都没有停下来等对方让路,而是都有很有礼貌的给对方让路,但是两个人都在不断朝路的同一个方向移动,这样只是在做无用功,还是不能让对方通过。

PCIe glossary

HBA

A host bus adapter (HBA) is a circuit board and/or integrated circuit adapter that provides input/output (I/O) processing and physical connectivity between a server and a storage device.

Because the HBA relieves the host microprocessor of both data storage and retrieval tasks, it can improve the server’s performance time.

Fat Trees

http://users.ics.forth.gr/~kateveni/534/03a/s52_benes.html

Example of PCIe sw process

https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Virtualization_Host_Configuration_and_Guest_Installation_Guide/chap-Virtualization_Host_Configuration_and_Guest_Installation_Guide-PCI_Device_Config.html