On Fri, May 08, 2020 at 10:24:43PM +, m...@netbsd.org wrote:
> The indirection only applies to the first call. The magic is within
> rtld.
You are comparing PLT calls with ifunc (where even normal PLT calls have
initial resolution overhead, but very tiny - while ifuncs may have
arbitrary first
On Fri, May 08, 2020 at 10:24:43PM +, m...@netbsd.org wrote:
>
> The indirection only applies to the first call. The magic is within
> rtld.
If it's not binary patch, no magic can avoid at least one level of
indirection.
--
Thor Lancelot Simon t...@p
On Fri, May 08, 2020 at 06:23:01PM -0400, Thor Lancelot Simon wrote:
> On Fri, May 08, 2020 at 10:03:06AM +0200, Kamil Rytarowski wrote:
> > On 08.05.2020 02:14, Thor Lancelot Simon wrote:
> > >
> > > Not without performance penalty for every atomic operation, unless you
> > > propose
> > > to do
On Fri, May 08, 2020 at 10:03:06AM +0200, Kamil Rytarowski wrote:
> On 08.05.2020 02:14, Thor Lancelot Simon wrote:
> >
> > Not without performance penalty for every atomic operation, unless you
> > propose
> > to do this by binary patch as is done in the kernel.
>
> There is atomic penalty, but
On Fri, May 08, 2020 at 04:09:02PM +0200, Kamil Rytarowski wrote:
> I object to opinions that libatomic is generally broken, if that would
> be the cause, it wouldn't be available and used on relatively all
> relevant generic purpose Operating Systems. Personally, I already
> received last year a f
On 08.05.2020 14:44, Martin Husemann wrote:
> On Fri, May 08, 2020 at 02:26:45PM +0200, Kamil Rytarowski wrote:
>> With _Atomic() we can mark any arbitrary struct to have serialized
>> accesses. As I said, with your attitude we shall remove FPU support (and
>> softfloat) as they are not async safe,
On Fri, May 08, 2020 at 02:44:14PM +0200, Martin Husemann wrote:
> On Fri, May 08, 2020 at 02:26:45PM +0200, Kamil Rytarowski wrote:
> > With _Atomic() we can mark any arbitrary struct to have serialized
> > accesses. As I said, with your attitude we shall remove FPU support (and
> > softfloat) as
On Fri, May 08, 2020 at 02:26:45PM +0200, Kamil Rytarowski wrote:
> With _Atomic() we can mark any arbitrary struct to have serialized
> accesses. As I said, with your attitude we shall remove FPU support (and
> softfloat) as they are not async safe, not safe in virtualization for
> MMU accesses an
On 08.05.2020 14:12, Joerg Sonnenberger wrote:
> On Thu, May 07, 2020 at 11:09:03PM +0200, Kamil Rytarowski wrote:
>>> (1) They introduce non-trivial blocking conditions, often defeating the
>>> reason for using atomics in first place.
>>> (2) They don't work in a constrained environment and are br
On Thu, May 07, 2020 at 10:49:39PM +, m...@netbsd.org wrote:
> I am under the impression that (at least GCC) compilers will not emit
> intrinsic calls if they are guaranteed to be available on the target.
This is true, but only a minor complication compared to the rest.
Joerg
On Thu, May 07, 2020 at 11:09:03PM +0200, Kamil Rytarowski wrote:
> > (1) They introduce non-trivial blocking conditions, often defeating the
> > reason for using atomics in first place.
> > (2) They don't work in a constrained environment and are broken by
> > common UNIX primitives like memory ma
On 08.05.2020 02:14, Thor Lancelot Simon wrote:
> On Fri, May 08, 2020 at 01:51:16AM +0200, Kamil Rytarowski wrote:
>> A runtime detection could be a part of ifunc (is it ready for NetBSD?).
>>
>> The standard C/C++ feature is to detect whether atomic operations are
>> real (lock-free) through atom
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