[M3devel] the need for cooperative suspend

Sat May 2 17:57:13 CEST 2015

Jay, 

Can you explain precisely what you mean by "suspend"?

A thread is suspended by ... a timer expiration?  Another thread at higher priority needing resources?

I'm thinking about a tight loop "for(;;) ;"... how do you stop a thread from running that (it could have
been coded in assembly...)?

Jay K writes:
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>We really need to move away from preemptive suspend.
>
>1) It is a large fraction of the target-dependent code in m3core.
>=20
>
>2) It doesn't really work in "wow64"=2C the x86-on-amd64 Windows system.
>The SuspendThread + GetThreadContext does not actually reliably give you
>current and coherent context.
>I'm not sure about x86-on-ia64.
>=20
>
> The context can be old.
> The context can be mid-update. Which might be ok=2C depending on what the =
>updates are.
> LIke if Eip and Esp are being updated=2C we don't care about Eip anyway.
>=20
>
>You can find out if either is the case=2C and let the thread run longer=2C
>but being in a long running syscall I believe is reported as possibly
>invalid even though it is valid.
>=20
>=20
>NT/native is ok.
>=20
>
>We should just use cooperative suspend and not worry about it.
>=20
>=20
>Thanks=2C
> - Jay
>
>
>=20
> 		 	   		  =
>
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><body class=3D'hmmessage'><div dir=3D'ltr'>We really need to move away from=
> preemptive suspend.<BR><br>1) It is a large fraction of the target-depende=
>nt code in m3core.<BR>&nbsp=3B<BR><br>2) It doesn't really work in "wow64"=
>=2C the x86-on-amd64 Windows system.<BR>The SuspendThread + GetThreadContex=
>t does not actually reliably give you<br>current and coherent context.<BR>I=
>'m not sure about x86-on-ia64.<BR>&nbsp=3B<BR><br>&nbsp=3BThe context can b=
>e old.<br>&nbsp=3BThe context can be mid-update. Which might be ok=2C depen=
>ding on what the updates are.<br>&nbsp=3BLIke if Eip and Esp are being upda=
>ted=2C we don't care about Eip anyway.<BR>&nbsp=3B<BR><br>You can find out =
>if either is the case=2C and let the thread run longer=2C<br>but being in a=
> long running syscall I believe is reported as possibly<br>invalid even tho=
>ugh it is valid.<BR>&nbsp=3B<BR>&nbsp=3B<BR>NT/native is ok.<BR>&nbsp=3B<BR=
>><br>We should just use cooperative suspend and not worry about it.<BR>&nbs=
>p=3B<BR>&nbsp=3B<BR>Thanks=2C<br>&nbsp=3B- Jay<br><br><br>&nbsp=3B<BR> 		 	=
>   		  </div></body>
></html>=
>
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