Article View: comp.arch
Article #10578Atomic operations (Was Re: Living With Old Baggage)
From: Eric Hamilton
Date: Thu, 02 May 1991 20:19
Date: Thu, 02 May 1991 20:19
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1459 bytes
In article <1991Apr22.175410.9840@decvax.dec.com>, kenton@abyss.zk3.dec.com (Jeff Kenton OSG/UEG) writes: |> |> The 88K has xmem, not test and set, which is guaranteed to be an atomic |> operation (the bus is locked between the read and write cycles). This |> can be used to create locks or compare and swap without disabling itnerrupts. |> Now I'm curious. How does one fabricate compare-and-swap out of xmem without disabling interrupts? Xmem has essentially the same restriction as test-and-set, which is that the stored value must be a constant independent of the loaded value. -- ---------------------------------------------------------------------- Eric Hamilton +1 919 248 6172 Data General Corporation hamilton@dg-rtp.rtp.dg.com 62 Alexander Drive ...!mcnc!rti!xyzzy!hamilton Research Triangle Park, NC 27709, USA
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!olivea!apple!amdcad!dgcad!dg-rtp!siberia!hamilton From: hamilton@siberia.rtp.dg.com (Eric Hamilton) Newsgroups: comp.arch Subject: Atomic operations (Was Re: Living With Old Baggage) Keywords: 68040 CAS2 Message-ID: <1991May2.201917.15062@dg-rtp.dg.com> Date: 2 May 91 20:19:17 GMT References: <336@scorpio.gtephx.UUCP> <12741@pt.cs.cmu.edu> <14628@encore.Encore.COM> <1991Apr22.175410.9840@decvax.dec.com> Sender: hamilton@siberia (Eric Hamilton) Organization: Data General Corporation, Research Triangle Park, NC Lines: 16