On Sat, Aug 6, 2011 at 12:37 PM, Daniel Baluta <daniel.bal...@gmail.com>wrote:
> On Sat, Aug 6, 2011 at 10:17 PM, subin gangadharan > <subingangadha...@gmail.com> wrote: > > Hi, > > This is a text excerpt from the article [1]. > > Below paragraph I didn't understand quite well.Mainly in bold > letters.Could > > anybody please explain how this will lead to an infinite loop. > > It seems self-explanatory. Most atomic ops are written to retry upon a > failed > store, and on PowerPC an atomic store to an unaligned address always > fails, > thus the processor will infinitely try to store the value, without having > the chance to fix the unaligned access (as would have happened if an > exception > was thrown). > > > > > Unfortunately, the PowerPC does not throw an exception when atomically > > storing to an unaligned address. Instead, the store simply always fails. > > This is bad because most atomic functions are written to retry upon a > failed > > store, under the assumption they were preempted. These two circumstances > > combine to where your program will go into an infinite loop if you > attempt > > to atomically store to an unaligned address. Oops. > > thanks, > Daniel. > Thanks Daniel, My bad, I was trying to connect the page fault explained before that paragraph and this one. Hence I got confused,again thanks for clarifying it. -- With Regards Subin Gangadharan Everything should be made as simple as possible,but not simpler.
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