Messages in this thread | | | Date | Fri, 15 Feb 2002 14:49:23 +0100 (CET) | From | Roman Zippel <> | Subject | Re: [PATCH] move task_struct allocation to arch |
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Hi,
On Fri, 15 Feb 2002, David Howells wrote:
> Firstly, in response to me having supplied a patch that made a set of four > byte-size values as the status area in the task_struct: > > | For the future, the biggest thing I'd like to see is actually to make > | "work" be a bitmap, because the "bytes are atomic" approach simply isn't > | portable anyway, so we might as well make things _explicitly_ atomic and > | use bit operations. Otherwise the alpha version of "work" would have to be > | four bytes per "bit" of information, which sounds really excessive.
As I mentioned before I more like the byte approach, since atomic bit field handling is quite expensive on most architectures, where a simple set/clear byte is only one or two instructions, if there is byte load/store instruction. So I'd really like to see to leave the decision to the architecture, whether to use bit or byte fields.
> And then after some discussion: > > | In particular, there's been all that discussion about cache-coloring the > | "struct task_struct", and my personal suggestion for that whole can of > | worms is to have the "struct low_level" be in the one low cache-line, and > | make it contain a pointer to "struct task_struct" - and just split the two > | up completely. Then the low-level asm code would never have to even look > | at "task_struct", it would only look at this stuff. > > (struct low_level became thread_info).
That I can agree with. :)
bye, Roman
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