On 4/12/07, Jeff Moyer <[EMAIL PROTECTED]> wrote:
I didn't see any response to Zach's request for code that actually tests out the shared ring buffer. Do you have such code?
Yes, I do. I was stress testing the code since last night. After 20+ hours of stress run with fio and aio-stress, now I'm posting it with confidence. I modified libaio's io_getevents to take advantage of new user level reap function. The feature is exported out via ring->compat_features. btw, is compat_feature suppose to be a version number or a bit mask? I think bitmask make more sense and more flexible. (warning: some lines are extremely long in the patch and my email client will probably mangle it badly). diff -Nurp libaio-0.3.104/src/io_getevents.c libaio-0.3.104-new/src/io_getevents.c --- libaio-0.3.104/src/io_getevents.c 2003-06-18 12:58:21.000000000 -0700 +++ libaio-0.3.104-new/src/io_getevents.c 2007-04-12 17:35:06.000000000 -0700 @@ -21,10 +21,13 @@ #include <stdlib.h> #include <time.h> #include "syscall.h" +#include <asm/system.h> io_syscall5(int, __io_getevents_0_4, io_getevents, io_context_t, ctx, long, min_nr, long, nr, struct io_event *, events, struct timespec *, timeout) #define AIO_RING_MAGIC 0xa10a10a1 +#define AIO_RING_BASE 1 +#define AIO_RING_USER_REAP 2 /* Ben will hate me for this */ struct aio_ring { @@ -41,7 +44,11 @@ struct aio_ring { int io_getevents_0_4(io_context_t ctx, long min_nr, long nr, struct io_event * events, struct timespec * timeout) { + long i = 0, ret; + unsigned head; + struct io_event *evt_base; struct aio_ring *ring; + ring = (struct aio_ring*)ctx; if (ring==NULL || ring->magic != AIO_RING_MAGIC) goto do_syscall; @@ -49,9 +56,35 @@ int io_getevents_0_4(io_context_t ctx, l if (ring->head == ring->tail) return 0; } - + + if (!(ring->compat_features & AIO_RING_USER_REAP)) + goto do_syscall; + + if (min_nr > nr || min_nr < 0 || nr < 0) + return -EINVAL; + + evt_base = (struct io_event *) (ring + 1); + while (i < nr) { + head = ring->head; + if (head == ring->tail) + break; + + *events = evt_base[head & (ring->nr - 1)]; + if (head == cmpxchg(&ring->head, head, head + 1)) { + events++; + i++; + } + } + + if (i >= min_nr) + return i; + do_syscall: - return __io_getevents_0_4(ctx, min_nr, nr, events, timeout); + ret = __io_getevents_0_4(ctx, min_nr - i, nr - i, events, timeout); + if (ret >= 0) + return i + ret; + else + return i ? i : ret; } DEFSYMVER(io_getevents_0_4, io_getevents, 0.4) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/