svn commit: r334545 - in head/sys: contrib/zstd/lib/freebsd kern netinet/libalias sys

[Gleb Smirnoff]

On Tue, Jun 05, 2018 at 06:35:37PM +0200, Mateusz Guzik wrote:
M> > On 06/02/2018 17:20, Mateusz Guzik wrote:
M> > > +#ifdef _KERNEL
M> > > +#define      malloc(size, type, flags) ({                            \
M> > > +     void *_malloc_item;                                             \
M> > > +     size_t _size = (size);                                          \
M> > > +     if (__builtin_constant_p(size) && __builtin_constant_p(flags) &&\
M> > > +         ((flags) & M_ZERO)) {                                       \
M> > > +             _malloc_item = malloc(_size, type, (flags) &~ M_ZERO);  \
M> > > +             if (((flags) & M_WAITOK) || _malloc_item != NULL)       \
M> > > +                     bzero(_malloc_item, _size);                     \
M> > > +     } else {                                                        \
M> > > +             _malloc_item = malloc(_size, type, flags);              \
M> > > +     }                                                               \
M> > > +     _malloc_item;                                                   \
M> > > +})
M> > > +#endif
M> >
M> > Mateusz,
M> >
M> > Thank you for this and for all of your performance work.  It is all very
M> > interesting stuff.
M> >
M> >
M> Thank you for the kind words. It is positive feedback like this which
M> keeps me going!

Btw, what was the point of checking flags || result? Most places in kernel
ignore flags and just test result regerdless of M_WAITOK/M_NOWAIT.

The result is already in a register, why do you think checking for absense
of M_WAITOK is faster that checking for !NULL _malloc_item?

-- 
Gleb Smirnoff