From 9817064b68fef7e4580c6df1ea597e106b9ff88b Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Fri, 28 Jul 2006 09:23:08 +0200 Subject: [PATCH] elevator: move the backmerging logic into the elevator core Right now, every IO scheduler implements its own backmerging (except for noop, which does no merging). That results in duplicated code for essentially the same operation, which is never a good thing. This patch moves the backmerging out of the io schedulers and into the elevator core. We save 1.6kb of text and as a bonus get backmerging for noop as well. Win-win! Signed-off-by: Jens Axboe --- include/linux/elevator.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux/elevator.h') diff --git a/include/linux/elevator.h b/include/linux/elevator.h index 1713ace808bf..2c270e90b33e 100644 --- a/include/linux/elevator.h +++ b/include/linux/elevator.h @@ -82,12 +82,14 @@ struct elevator_queue struct kobject kobj; struct elevator_type *elevator_type; struct mutex sysfs_lock; + struct hlist_head *hash; }; /* * block elevator interface */ extern void elv_dispatch_sort(request_queue_t *, struct request *); +extern void elv_dispatch_add_tail(request_queue_t *, struct request *); extern void elv_add_request(request_queue_t *, struct request *, int, int); extern void __elv_add_request(request_queue_t *, struct request *, int, int); extern void elv_insert(request_queue_t *, struct request *, int); -- cgit v1.2.3 From 2e662b65f05d550b6799ed6bfa9963b82279e6b7 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Thu, 13 Jul 2006 11:55:04 +0200 Subject: [PATCH] elevator: abstract out the rbtree sort handling The rbtree sort/lookup/reposition logic is mostly duplicated in cfq/deadline/as, so move it to the elevator core. The io schedulers still provide the actual rb root, as we don't want to impose any sort of specific handling on the schedulers. Introduce the helpers and rb_node in struct request to help migrate the IO schedulers. Signed-off-by: Jens Axboe --- include/linux/elevator.h | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) (limited to 'include/linux/elevator.h') diff --git a/include/linux/elevator.h b/include/linux/elevator.h index 2c270e90b33e..95b2a04b969c 100644 --- a/include/linux/elevator.h +++ b/include/linux/elevator.h @@ -6,7 +6,7 @@ typedef int (elevator_merge_fn) (request_queue_t *, struct request **, typedef void (elevator_merge_req_fn) (request_queue_t *, struct request *, struct request *); -typedef void (elevator_merged_fn) (request_queue_t *, struct request *); +typedef void (elevator_merged_fn) (request_queue_t *, struct request *, int); typedef int (elevator_dispatch_fn) (request_queue_t *, int); @@ -96,7 +96,7 @@ extern void elv_insert(request_queue_t *, struct request *, int); extern int elv_merge(request_queue_t *, struct request **, struct bio *); extern void elv_merge_requests(request_queue_t *, struct request *, struct request *); -extern void elv_merged_request(request_queue_t *, struct request *); +extern void elv_merged_request(request_queue_t *, struct request *, int); extern void elv_dequeue_request(request_queue_t *, struct request *); extern void elv_requeue_request(request_queue_t *, struct request *); extern int elv_queue_empty(request_queue_t *); @@ -126,6 +126,19 @@ extern int elevator_init(request_queue_t *, char *); extern void elevator_exit(elevator_t *); extern int elv_rq_merge_ok(struct request *, struct bio *); +/* + * Helper functions. + */ +extern struct request *elv_rb_former_request(request_queue_t *, struct request *); +extern struct request *elv_rb_latter_request(request_queue_t *, struct request *); + +/* + * rb support functions. + */ +extern struct request *elv_rb_add(struct rb_root *, struct request *); +extern void elv_rb_del(struct rb_root *, struct request *); +extern struct request *elv_rb_find(struct rb_root *, sector_t); + /* * Return values from elevator merger */ @@ -151,5 +164,6 @@ enum { }; #define rq_end_sector(rq) ((rq)->sector + (rq)->nr_sectors) +#define rb_entry_rq(node) rb_entry((node), struct request, rb_node) #endif -- cgit v1.2.3 From 1fbfdfcddff4df188b24d9d05271a76a85064583 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Tue, 11 Jul 2006 21:49:15 +0200 Subject: [PATCH] elevator: introduce a way to reuse rq for internal FIFO handling The io schedulers can use this instead of having to allocate space for it themselves. Signed-off-by: Jens Axboe --- include/linux/elevator.h | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'include/linux/elevator.h') diff --git a/include/linux/elevator.h b/include/linux/elevator.h index 95b2a04b969c..0e7b1a733919 100644 --- a/include/linux/elevator.h +++ b/include/linux/elevator.h @@ -166,4 +166,16 @@ enum { #define rq_end_sector(rq) ((rq)->sector + (rq)->nr_sectors) #define rb_entry_rq(node) rb_entry((node), struct request, rb_node) +/* + * Hack to reuse the donelist list_head as the fifo time holder while + * the request is in the io scheduler. Saves an unsigned long in rq. + */ +#define rq_fifo_time(rq) ((unsigned long) (rq)->donelist.next) +#define rq_set_fifo_time(rq,exp) ((rq)->donelist.next = (void *) (exp)) +#define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist) +#define rq_fifo_clear(rq) do { \ + list_del_init(&(rq)->queuelist); \ + INIT_LIST_HEAD(&(rq)->donelist); \ + } while (0) + #endif -- cgit v1.2.3 From cb78b285c8f9d59b0d4e4f6a54c2977ce1d9b880 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Fri, 28 Jul 2006 09:32:57 +0200 Subject: [PATCH] Drop useless bio passing in may_queue/set_request API It's not needed for anything, so kill the bio passing. Signed-off-by: Jens Axboe --- include/linux/elevator.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'include/linux/elevator.h') diff --git a/include/linux/elevator.h b/include/linux/elevator.h index 0e7b1a733919..cc81645a3e18 100644 --- a/include/linux/elevator.h +++ b/include/linux/elevator.h @@ -14,9 +14,9 @@ typedef void (elevator_add_req_fn) (request_queue_t *, struct request *); typedef int (elevator_queue_empty_fn) (request_queue_t *); typedef struct request *(elevator_request_list_fn) (request_queue_t *, struct request *); typedef void (elevator_completed_req_fn) (request_queue_t *, struct request *); -typedef int (elevator_may_queue_fn) (request_queue_t *, int, struct bio *); +typedef int (elevator_may_queue_fn) (request_queue_t *, int); -typedef int (elevator_set_req_fn) (request_queue_t *, struct request *, struct bio *, gfp_t); +typedef int (elevator_set_req_fn) (request_queue_t *, struct request *, gfp_t); typedef void (elevator_put_req_fn) (request_queue_t *, struct request *); typedef void (elevator_activate_req_fn) (request_queue_t *, struct request *); typedef void (elevator_deactivate_req_fn) (request_queue_t *, struct request *); @@ -105,9 +105,9 @@ extern struct request *elv_former_request(request_queue_t *, struct request *); extern struct request *elv_latter_request(request_queue_t *, struct request *); extern int elv_register_queue(request_queue_t *q); extern void elv_unregister_queue(request_queue_t *q); -extern int elv_may_queue(request_queue_t *, int, struct bio *); +extern int elv_may_queue(request_queue_t *, int); extern void elv_completed_request(request_queue_t *, struct request *); -extern int elv_set_request(request_queue_t *, struct request *, struct bio *, gfp_t); +extern int elv_set_request(request_queue_t *, struct request *, gfp_t); extern void elv_put_request(request_queue_t *, struct request *); /* -- cgit v1.2.3 From 4a893e837bb470867d74c05d6c6b97bba5a96185 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Sat, 22 Jul 2006 15:37:43 +0200 Subject: [PATCH] elevator: define ioc counting mechanism None of the in-kernel primitives for handling "atomic" counting seem to be a good fit. We need something that is essentially free for incrementing/decrementing, while the read side may be more expensive as we only ever need to do that when a device is removed from the kernel. Use a per-cpu variable for maintaining a per-cpu ioc count and define a reading mechanism that just sums up the values. Signed-off-by: Jens Axboe --- include/linux/elevator.h | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) (limited to 'include/linux/elevator.h') diff --git a/include/linux/elevator.h b/include/linux/elevator.h index cc81645a3e18..9c5a04f6114c 100644 --- a/include/linux/elevator.h +++ b/include/linux/elevator.h @@ -1,6 +1,8 @@ #ifndef _LINUX_ELEVATOR_H #define _LINUX_ELEVATOR_H +#include + typedef int (elevator_merge_fn) (request_queue_t *, struct request **, struct bio *); @@ -178,4 +180,27 @@ enum { INIT_LIST_HEAD(&(rq)->donelist); \ } while (0) +/* + * io context count accounting + */ +#define elv_ioc_count_mod(name, __val) \ + do { \ + preempt_disable(); \ + __get_cpu_var(name) += (__val); \ + preempt_enable(); \ + } while (0) + +#define elv_ioc_count_inc(name) elv_ioc_count_mod(name, 1) +#define elv_ioc_count_dec(name) elv_ioc_count_mod(name, -1) + +#define elv_ioc_count_read(name) \ +({ \ + unsigned long __val = 0; \ + int __cpu; \ + smp_wmb(); \ + for_each_possible_cpu(__cpu) \ + __val += per_cpu(name, __cpu); \ + __val; \ +}) + #endif -- cgit v1.2.3 From 9361401eb7619c033e2394e4f9f6d410d6719ac7 Mon Sep 17 00:00:00 2001 From: David Howells Date: Sat, 30 Sep 2006 20:45:40 +0200 Subject: [PATCH] BLOCK: Make it possible to disable the block layer [try #6] Make it possible to disable the block layer. Not all embedded devices require it, some can make do with just JFFS2, NFS, ramfs, etc - none of which require the block layer to be present. This patch does the following: (*) Introduces CONFIG_BLOCK to disable the block layer, buffering and blockdev support. (*) Adds dependencies on CONFIG_BLOCK to any configuration item that controls an item that uses the block layer. This includes: (*) Block I/O tracing. (*) Disk partition code. (*) All filesystems that are block based, eg: Ext3, ReiserFS, ISOFS. (*) The SCSI layer. As far as I can tell, even SCSI chardevs use the block layer to do scheduling. Some drivers that use SCSI facilities - such as USB storage - end up disabled indirectly from this. (*) Various block-based device drivers, such as IDE and the old CDROM drivers. (*) MTD blockdev handling and FTL. (*) JFFS - which uses set_bdev_super(), something it could avoid doing by taking a leaf out of JFFS2's book. (*) Makes most of the contents of linux/blkdev.h, linux/buffer_head.h and linux/elevator.h contingent on CONFIG_BLOCK being set. sector_div() is, however, still used in places, and so is still available. (*) Also made contingent are the contents of linux/mpage.h, linux/genhd.h and parts of linux/fs.h. (*) Makes a number of files in fs/ contingent on CONFIG_BLOCK. (*) Makes mm/bounce.c (bounce buffering) contingent on CONFIG_BLOCK. (*) set_page_dirty() doesn't call __set_page_dirty_buffers() if CONFIG_BLOCK is not enabled. (*) fs/no-block.c is created to hold out-of-line stubs and things that are required when CONFIG_BLOCK is not set: (*) Default blockdev file operations (to give error ENODEV on opening). (*) Makes some /proc changes: (*) /proc/devices does not list any blockdevs. (*) /proc/diskstats and /proc/partitions are contingent on CONFIG_BLOCK. (*) Makes some compat ioctl handling contingent on CONFIG_BLOCK. (*) If CONFIG_BLOCK is not defined, makes sys_quotactl() return -ENODEV if given command other than Q_SYNC or if a special device is specified. (*) In init/do_mounts.c, no reference is made to the blockdev routines if CONFIG_BLOCK is not defined. This does not prohibit NFS roots or JFFS2. (*) The bdflush, ioprio_set and ioprio_get syscalls can now be absent (return error ENOSYS by way of cond_syscall if so). (*) The seclvl_bd_claim() and seclvl_bd_release() security calls do nothing if CONFIG_BLOCK is not set, since they can't then happen. Signed-Off-By: David Howells Signed-off-by: Jens Axboe --- include/linux/elevator.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include/linux/elevator.h') diff --git a/include/linux/elevator.h b/include/linux/elevator.h index 9c5a04f6114c..b3370ef5164d 100644 --- a/include/linux/elevator.h +++ b/include/linux/elevator.h @@ -3,6 +3,8 @@ #include +#ifdef CONFIG_BLOCK + typedef int (elevator_merge_fn) (request_queue_t *, struct request **, struct bio *); @@ -203,4 +205,5 @@ enum { __val; \ }) +#endif /* CONFIG_BLOCK */ #endif -- cgit v1.2.3