Messages in this thread Patch in this message | | | Date | Fri, 20 Jan 2006 15:17:34 -0800 | From | Nate Diller <> | Subject | [PATCH 1/2][RESEND] Default iosched fixes (was: Fall back io scheduler for 2.6.15?) |
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My previous default iosched patch did a poor job dealing with the 'elevator=' boot-time option. The old behavior falls back to the compiled-in default if the requested one is not registered at boot time. This patch dynamically evaluates which default to use, and emits a suitable error message when the requested scheduler is not available. It also does the 'as' -> 'anticipatory' conversion before elevator registration, which along with a modified registration function, allows it to correctly indicate which default scheduler is in use.
Tested for a range of boot options on 2.6.16-rc1-mm2.
Signed-off-by: Nate Diller <nate.diller@gmail.com>
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Jens: i'm submitting this seperately from the objectionable 'modular default scheduler' check. Is there anything else I should change?
--- ./block/elevator.c 2006-01-20 13:47:16.000000000 -0800 +++ ./block/elevator.c 2006-01-20 14:52:53.000000000 -0800 @@ -140,35 +140,16 @@ static int elevator_attach(request_queue
static char chosen_elevator[16];
-static void elevator_setup_default(void) +static int __init elevator_setup(char *str) { - struct elevator_type *e; - - /* - * If default has not been set, use the compiled-in selection. - */ - if (!chosen_elevator[0]) - strcpy(chosen_elevator, CONFIG_DEFAULT_IOSCHED); - /* * Be backwards-compatible with previous kernels, so users * won't get the wrong elevator. */ - if (!strcmp(chosen_elevator, "as")) + if (!strcmp(str, "as")) strcpy(chosen_elevator, "anticipatory"); - - /* - * If the given scheduler is not available, fall back to the default - */ - if ((e = elevator_find(chosen_elevator))) - elevator_put(e); else - strcpy(chosen_elevator, CONFIG_DEFAULT_IOSCHED); -} - -static int __init elevator_setup(char *str) -{ - strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); + strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); return 0; }
@@ -185,15 +166,15 @@ int elevator_init(request_queue_t *q, ch q->end_sector = 0; q->boundary_rq = NULL;
- elevator_setup_default(); - - if (!name) - name = chosen_elevator; - - e = elevator_get(name); - if (!e) + if (name && !(e = elevator_get(name))) return -EINVAL;
+ if (!e && !(e = elevator_get(chosen_elevator))) { + e = elevator_get(CONFIG_DEFAULT_IOSCHED); + if (*chosen_elevator) + printk("I/O scheduler %s not found\n", chosen_elevator); + } + eq = kmalloc(sizeof(struct elevator_queue), GFP_KERNEL); if (!eq) { elevator_put(e); @@ -681,8 +662,10 @@ int elv_register(struct elevator_type *e spin_unlock_irq(&elv_list_lock);
printk(KERN_INFO "io scheduler %s registered", e->elevator_name); - if (!strcmp(e->elevator_name, chosen_elevator)) - printk(" (default)"); + if (!strcmp(e->elevator_name, chosen_elevator) || + (!*chosen_elevator && + !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED))) + printk(" (default)"); printk("\n"); return 0; } - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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