Post z dnia: 28/12/2006

Pierwsze skojarzenie do slowa “elf” ?

Format plikow wykonywalnych … ( zostalo mi po zabawach z infekcjami ELFow z phracka )

Do slowa “cos” ? y=A*cos(2*Pi*f+fi). Pytanie: czy jestem chory i nienormalny ( ktos do mnie na GG napisal “cos” – w sensie jakiejs rzeczy a mi sie skojarzylo … )

Ciekawostka/OpenSolaris o (nie)cachowaniu pewnych requestow IO w kernelu:

/usr/src/uts/common/syscall/rw.c ( syscalle read(),write() i pochodne ):


54 #define COPYOUT_MAX_CACHE (1<<17) /* 128K */
55
56 size_t copyout_max_cached = COPYOUT_MAX_CACHE; /* global so it's patchable */

71 /*
72 * Native system call
73 */
74 ssize_t
75 read(int fdes, void *cbuf, size_t count)
166 /*
167 * Only use bypass caches when the count is large enough
168 */
169 if (bcount <= copyout_max_cached)
170    auio.uio_extflg = UIO_COPY_CACHED;
171 else
172    auio.uio_extflg = UIO_COPY_DEFAULT;

Identycznie jest dla write(). Z jakiegos *.h #define’y:


/*
* uio_extflg: extended flags
*
* NOTE: This flag will be used in uiomove to determine
* if non-temporal access, ie, access bypassing caches,
* should be used. Filesystems that don't initialize this
* field could experience suboptimal performance due to
* the random data the field contains.
*/

/* no special options to copy */
#define UIO_COPY_DEFAULT 0x0000

/* copy should not bypass caches */
#define UIO_COPY_CACHED 0x0001

Comments are closed.