[tarantool-patches] Re: [PATCH 2/3] Proper unwind for currently executing fiber
Georgy Kirichenko
georgy at tarantool.org
Wed Sep 26 09:57:07 MSK 2018
On Wednesday, September 26, 2018 2:34:02 AM MSK Konstantin Osipov wrote:
> * Georgy Kirichenko <georgy at tarantool.org> [18/09/22 00:21]:
> > A fiber's coro context stores execution state for a corresponding
> > already yielded fiber. If fiber is on the execution then it hasn't
> > valid stored coro state and might be backtraced without a special unwind
> > context builder.
>
> I did not understand what's going on from the comment. I assume
> this is an optimization, in which you try to avoid re-fetching the
> registers in some cases?
>
> Please clarify.
>
> > --
Each yielded fiber has a preserved coro state stored in a corresponding
variable however an executing fiber has a volatile state placed in CPU
registers (stack pointer, instruction pointer and non-volatile registers) and
corresponding context-storing variable value is invalid.
For already yielded fiber we use a special asm-written handler to make a
temporary switch to the preserved state and capture executing context what is
not needed for executing fiber.
After the patch for the executing fiber NULL is passed to the backtrace
function as coro context and then backtrace function could decide should it
use special context-switching handler or might just use unw_getcontext from
the unwind library.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 488 bytes
Desc: This is a digitally signed message part.
URL: <https://lists.tarantool.org/pipermail/tarantool-patches/attachments/20180926/3c3cc056/attachment.sig>
More information about the Tarantool-patches
mailing list