Alpha load locked granularity

Article: Haswell Transactional Memory Alternatives
By: anon (anon.delete@this.anon.com), September 2, 2012 6:23 pm
Room: Moderated Discussions
Paul A. Clayton (paaronclayton.delete@this.gmail.com) on September 1, 2012 7:29 am wrote:
> rwessel (robertwessel.delete@this.yahoo.com) on August 31, 2012 8:54 pm
> wrote:
> > Paul A. Clayton (paaronclayton.delete@this.gmail.com) on
> >
> August 28, 2012 10:28 am wrote:
> [snip]
> >> (The Alpha architectural
> suggestion for portability of not
> >> placing two atomic operands within
> the same 8 KiB page seems
> >> a bit excessive.)
> [snip]
> > While it
> might have been changed subsequently, the original
> > Alpha architectural
> suggestion was that such items be quadword
> > aligned and in their own
> "large cache block", which were defined as "likely
> > be(ing) 32, 64, 128 or
> 256 bytes".
>
> I seem to have misinterpreted a statement in version 4 (1998) of
> the Alpha Architecture Handbook--"A processor’s locked range is the aligned
> block of 2**N bytes that includes the locked_physical_address. The 2**N value is
> implementation dependent. It is at least 16 (minimum lock range is an aligned
> 16-byte block) and is at most the page size for that implementation (maximum
> lock range is one physical
> page)."--and did not remember another statement just
> a page later--"Hardware implementations are encouraged to lock no more than 128
> bytes. Software implementations are encouraged to separate locked locations by
> at least 128 bytes from
> other locations that could potentially be written by
> another processor while the first location is locked."
>
> It seems Alpha did
> settle on a single "recommended" number, though I think allowing for page-sized
> granularity might be excessive. (An implementation could--at some complexity
> cost--still use primarily page-sized coherence while supporting a finer
> granularity for LLDx_L/STx_C, though 8KiB seems excessively large for the common
> coherence granularity.)
>
> (Of course, Alpha did eventually support 64 KiB base
> pages.)

Didn't Alpha always support 64 KB, in addition to 8 KB, 512 KB, and 2 MB page sizes?
< Previous Post in ThreadNext Post in Thread >
TopicPosted ByDate
Article: Haswell TM AlternativesDavid Kanter08/21/12 10:17 PM
  Article: Haswell TM AlternativesHåkan Winbom08/22/12 12:52 AM
    Article: Haswell TM AlternativesDavid Kanter08/22/12 02:06 AM
  Article: Haswell TM Alternativesanon08/22/12 09:46 AM
    Article: Haswell TM AlternativesLinus Torvalds08/22/12 10:16 AM
      Article: Haswell TM AlternativesDoug S08/24/12 09:34 AM
    AMD's ASF even more limitedPaul A. Clayton08/22/12 10:20 AM
      AMD's ASF even more limitedLinus Torvalds08/22/12 10:41 AM
        Compiler use of ll/sc?Paul A. Clayton08/28/12 10:28 AM
          Compiler use of ll/sc?Linus Torvalds09/08/12 01:58 PM
            Lock recognition?Paul A. Clayton09/10/12 02:17 PM
              Sorry, I was confusedPaul A. Clayton09/13/12 11:56 AM
  Filter to detect store conflictsPaul A. Clayton08/22/12 10:19 AM
  Article: Haswell TM Alternativesbakaneko08/22/12 03:02 PM
    Article: Haswell TM AlternativesDavid Kanter08/22/12 03:45 PM
      Article: Haswell TM Alternativesbakaneko08/22/12 10:56 PM
  Cache line granularity?Paul A. Clayton08/28/12 10:28 AM
    Cache line granularity?David Kanter08/31/12 09:13 AM
      A looser definition might have advantagesPaul A. Clayton09/01/12 07:29 AM
    Cache line granularity?rwessel08/31/12 08:54 PM
      Alpha load locked granularityPaul A. Clayton09/01/12 07:29 AM
        Alpha load locked granularityanon09/02/12 06:23 PM
          Alpha pages groupsPaul A. Clayton09/03/12 05:16 AM
  An alternative implementationMaynard Handley11/20/12 10:52 PM
    An alternative implementationbakaneko11/21/12 06:52 AM
      Guarding unread values?Paul A. Clayton11/21/12 09:39 AM
        Guarding unread values?bakaneko11/21/12 12:25 PM
    TM granularity and versioningPaul A. Clayton11/21/12 09:27 AM
      TM granularity and versioningMaynard Handley11/21/12 11:52 AM
        Indeed, TM (and coherence) has devilish details (NT)Paul A. Clayton11/21/12 11:56 AM
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