From 6a421c1dc94b12923294a359822346f12492de5e Mon Sep 17 00:00:00 2001 From: Aaron Carroll Date: Thu, 14 Aug 2008 18:17:15 +1000 Subject: block: update documentation for deadline fifo_batch tunable Update the description of fifo_batch to match the current implementation, and include a description of how to tune it. Signed-off-by: Aaron Carroll Signed-off-by: Jens Axboe --- Documentation/block/deadline-iosched.txt | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) (limited to 'Documentation') diff --git a/Documentation/block/deadline-iosched.txt b/Documentation/block/deadline-iosched.txt index c23cab13c3d1..72576769e0f4 100644 --- a/Documentation/block/deadline-iosched.txt +++ b/Documentation/block/deadline-iosched.txt @@ -30,12 +30,18 @@ write_expire (in ms) Similar to read_expire mentioned above, but for writes. -fifo_batch +fifo_batch (number of requests) ---------- -When a read request expires its deadline, we must move some requests from -the sorted io scheduler list to the block device dispatch queue. fifo_batch -controls how many requests we move. +Requests are grouped into ``batches'' of a particular data direction (read or +write) which are serviced in increasing sector order. To limit extra seeking, +deadline expiries are only checked between batches. fifo_batch controls the +maximum number of requests per batch. + +This parameter tunes the balance between per-request latency and aggregate +throughput. When low latency is the primary concern, smaller is better (where +a value of 1 yields first-come first-served behaviour). Increasing fifo_batch +generally improves throughput, at the cost of latency variation. writes_starved (number of dispatches) -- cgit v1.2.3-58-ga151 From 710027a48ede75428cc68eaa8ae2269b1e356e2c Mon Sep 17 00:00:00 2001 From: Randy Dunlap Date: Tue, 19 Aug 2008 20:13:11 +0200 Subject: Add some block/ source files to the kernel-api docbook. Fix kernel-doc notation in them as needed. Fix changed function parameter names. Fix typos/spellos. In comments, change REQ_SPECIAL to REQ_TYPE_SPECIAL and REQ_BLOCK_PC to REQ_TYPE_BLOCK_PC. Signed-off-by: Randy Dunlap Signed-off-by: Jens Axboe --- Documentation/DocBook/kernel-api.tmpl | 4 ++ block/blk-core.c | 72 +++++++++++++++++------------------ block/blk-exec.c | 6 +-- block/blk-integrity.c | 4 +- block/blk-map.c | 16 ++++---- block/blk-settings.c | 8 ++-- block/blk-tag.c | 8 ++-- block/genhd.c | 5 ++- 8 files changed, 64 insertions(+), 59 deletions(-) (limited to 'Documentation') diff --git a/Documentation/DocBook/kernel-api.tmpl b/Documentation/DocBook/kernel-api.tmpl index b7b1482f6e04..f5696ba9ae96 100644 --- a/Documentation/DocBook/kernel-api.tmpl +++ b/Documentation/DocBook/kernel-api.tmpl @@ -364,6 +364,10 @@ X!Edrivers/pnp/system.c !Eblock/blk-barrier.c !Eblock/blk-tag.c !Iblock/blk-tag.c +!Eblock/blk-integrity.c +!Iblock/blktrace.c +!Iblock/genhd.c +!Eblock/genhd.c diff --git a/block/blk-core.c b/block/blk-core.c index 2616cdd049a8..86d22e7d65c5 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -531,7 +531,7 @@ EXPORT_SYMBOL(blk_alloc_queue_node); * request queue; this lock will be taken also from interrupt context, so irq * disabling is needed for it. * - * Function returns a pointer to the initialized request queue, or NULL if + * Function returns a pointer to the initialized request queue, or %NULL if * it didn't succeed. * * Note: @@ -913,7 +913,7 @@ void blk_requeue_request(struct request_queue *q, struct request *rq) EXPORT_SYMBOL(blk_requeue_request); /** - * blk_insert_request - insert a special request in to a request queue + * blk_insert_request - insert a special request into a request queue * @q: request queue where request should be inserted * @rq: request to be inserted * @at_head: insert request at head or tail of queue @@ -923,8 +923,8 @@ EXPORT_SYMBOL(blk_requeue_request); * Many block devices need to execute commands asynchronously, so they don't * block the whole kernel from preemption during request execution. This is * accomplished normally by inserting aritficial requests tagged as - * REQ_SPECIAL in to the corresponding request queue, and letting them be - * scheduled for actual execution by the request queue. + * REQ_TYPE_SPECIAL in to the corresponding request queue, and letting them + * be scheduled for actual execution by the request queue. * * We have the option of inserting the head or the tail of the queue. * Typically we use the tail for new ioctls and so forth. We use the head @@ -1322,7 +1322,7 @@ static inline int bio_check_eod(struct bio *bio, unsigned int nr_sectors) } /** - * generic_make_request: hand a buffer to its device driver for I/O + * generic_make_request - hand a buffer to its device driver for I/O * @bio: The bio describing the location in memory and on the device. * * generic_make_request() is used to make I/O requests of block @@ -1480,13 +1480,13 @@ void generic_make_request(struct bio *bio) EXPORT_SYMBOL(generic_make_request); /** - * submit_bio: submit a bio to the block device layer for I/O + * submit_bio - submit a bio to the block device layer for I/O * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead) * @bio: The &struct bio which describes the I/O * * submit_bio() is very similar in purpose to generic_make_request(), and * uses that function to do most of the work. Both are fairly rough - * interfaces, @bio must be presetup and ready for I/O. + * interfaces; @bio must be presetup and ready for I/O. * */ void submit_bio(int rw, struct bio *bio) @@ -1524,7 +1524,7 @@ EXPORT_SYMBOL(submit_bio); /** * __end_that_request_first - end I/O on a request * @req: the request being processed - * @error: 0 for success, < 0 for error + * @error: %0 for success, < %0 for error * @nr_bytes: number of bytes to complete * * Description: @@ -1532,8 +1532,8 @@ EXPORT_SYMBOL(submit_bio); * for the next range of segments (if any) in the cluster. * * Return: - * 0 - we are done with this request, call end_that_request_last() - * 1 - still buffers pending for this request + * %0 - we are done with this request, call end_that_request_last() + * %1 - still buffers pending for this request **/ static int __end_that_request_first(struct request *req, int error, int nr_bytes) @@ -1544,7 +1544,7 @@ static int __end_that_request_first(struct request *req, int error, blk_add_trace_rq(req->q, req, BLK_TA_COMPLETE); /* - * for a REQ_BLOCK_PC request, we want to carry any eventual + * for a REQ_TYPE_BLOCK_PC request, we want to carry any eventual * sense key with us all the way through */ if (!blk_pc_request(req)) @@ -1810,11 +1810,11 @@ EXPORT_SYMBOL_GPL(blk_rq_cur_bytes); /** * end_queued_request - end all I/O on a queued request * @rq: the request being processed - * @uptodate: error value or 0/1 uptodate flag + * @uptodate: error value or %0/%1 uptodate flag * * Description: * Ends all I/O on a request, and removes it from the block layer queues. - * Not suitable for normal IO completion, unless the driver still has + * Not suitable for normal I/O completion, unless the driver still has * the request attached to the block layer. * **/ @@ -1827,7 +1827,7 @@ EXPORT_SYMBOL(end_queued_request); /** * end_dequeued_request - end all I/O on a dequeued request * @rq: the request being processed - * @uptodate: error value or 0/1 uptodate flag + * @uptodate: error value or %0/%1 uptodate flag * * Description: * Ends all I/O on a request. The request must already have been @@ -1845,14 +1845,14 @@ EXPORT_SYMBOL(end_dequeued_request); /** * end_request - end I/O on the current segment of the request * @req: the request being processed - * @uptodate: error value or 0/1 uptodate flag + * @uptodate: error value or %0/%1 uptodate flag * * Description: * Ends I/O on the current segment of a request. If that is the only * remaining segment, the request is also completed and freed. * - * This is a remnant of how older block drivers handled IO completions. - * Modern drivers typically end IO on the full request in one go, unless + * This is a remnant of how older block drivers handled I/O completions. + * Modern drivers typically end I/O on the full request in one go, unless * they have a residual value to account for. For that case this function * isn't really useful, unless the residual just happens to be the * full current segment. In other words, don't use this function in new @@ -1870,12 +1870,12 @@ EXPORT_SYMBOL(end_request); /** * blk_end_io - Generic end_io function to complete a request. * @rq: the request being processed - * @error: 0 for success, < 0 for error + * @error: %0 for success, < %0 for error * @nr_bytes: number of bytes to complete @rq * @bidi_bytes: number of bytes to complete @rq->next_rq * @drv_callback: function called between completion of bios in the request * and completion of the request. - * If the callback returns non 0, this helper returns without + * If the callback returns non %0, this helper returns without * completion of the request. * * Description: @@ -1883,8 +1883,8 @@ EXPORT_SYMBOL(end_request); * If @rq has leftover, sets it up for the next range of segments. * * Return: - * 0 - we are done with this request - * 1 - this request is not freed yet, it still has pending buffers. + * %0 - we are done with this request + * %1 - this request is not freed yet, it still has pending buffers. **/ static int blk_end_io(struct request *rq, int error, unsigned int nr_bytes, unsigned int bidi_bytes, @@ -1919,7 +1919,7 @@ static int blk_end_io(struct request *rq, int error, unsigned int nr_bytes, /** * blk_end_request - Helper function for drivers to complete the request. * @rq: the request being processed - * @error: 0 for success, < 0 for error + * @error: %0 for success, < %0 for error * @nr_bytes: number of bytes to complete * * Description: @@ -1927,8 +1927,8 @@ static int blk_end_io(struct request *rq, int error, unsigned int nr_bytes, * If @rq has leftover, sets it up for the next range of segments. * * Return: - * 0 - we are done with this request - * 1 - still buffers pending for this request + * %0 - we are done with this request + * %1 - still buffers pending for this request **/ int blk_end_request(struct request *rq, int error, unsigned int nr_bytes) { @@ -1939,15 +1939,15 @@ EXPORT_SYMBOL_GPL(blk_end_request); /** * __blk_end_request - Helper function for drivers to complete the request. * @rq: the request being processed - * @error: 0 for success, < 0 for error + * @error: %0 for success, < %0 for error * @nr_bytes: number of bytes to complete * * Description: * Must be called with queue lock held unlike blk_end_request(). * * Return: - * 0 - we are done with this request - * 1 - still buffers pending for this request + * %0 - we are done with this request + * %1 - still buffers pending for this request **/ int __blk_end_request(struct request *rq, int error, unsigned int nr_bytes) { @@ -1966,7 +1966,7 @@ EXPORT_SYMBOL_GPL(__blk_end_request); /** * blk_end_bidi_request - Helper function for drivers to complete bidi request. * @rq: the bidi request being processed - * @error: 0 for success, < 0 for error + * @error: %0 for success, < %0 for error * @nr_bytes: number of bytes to complete @rq * @bidi_bytes: number of bytes to complete @rq->next_rq * @@ -1974,8 +1974,8 @@ EXPORT_SYMBOL_GPL(__blk_end_request); * Ends I/O on a number of bytes attached to @rq and @rq->next_rq. * * Return: - * 0 - we are done with this request - * 1 - still buffers pending for this request + * %0 - we are done with this request + * %1 - still buffers pending for this request **/ int blk_end_bidi_request(struct request *rq, int error, unsigned int nr_bytes, unsigned int bidi_bytes) @@ -1987,11 +1987,11 @@ EXPORT_SYMBOL_GPL(blk_end_bidi_request); /** * blk_end_request_callback - Special helper function for tricky drivers * @rq: the request being processed - * @error: 0 for success, < 0 for error + * @error: %0 for success, < %0 for error * @nr_bytes: number of bytes to complete * @drv_callback: function called between completion of bios in the request * and completion of the request. - * If the callback returns non 0, this helper returns without + * If the callback returns non %0, this helper returns without * completion of the request. * * Description: @@ -2004,10 +2004,10 @@ EXPORT_SYMBOL_GPL(blk_end_bidi_request); * Don't use this interface in other places anymore. * * Return: - * 0 - we are done with this request - * 1 - this request is not freed yet. - * this request still has pending buffers or - * the driver doesn't want to finish this request yet. + * %0 - we are done with this request + * %1 - this request is not freed yet. + * this request still has pending buffers or + * the driver doesn't want to finish this request yet. **/ int blk_end_request_callback(struct request *rq, int error, unsigned int nr_bytes, diff --git a/block/blk-exec.c b/block/blk-exec.c index 9bceff7674f2..6af716d1e54e 100644 --- a/block/blk-exec.c +++ b/block/blk-exec.c @@ -16,7 +16,7 @@ /** * blk_end_sync_rq - executes a completion event on a request * @rq: request to complete - * @error: end io status of the request + * @error: end I/O status of the request */ static void blk_end_sync_rq(struct request *rq, int error) { @@ -41,7 +41,7 @@ static void blk_end_sync_rq(struct request *rq, int error) * @done: I/O completion handler * * Description: - * Insert a fully prepared request at the back of the io scheduler queue + * Insert a fully prepared request at the back of the I/O scheduler queue * for execution. Don't wait for completion. */ void blk_execute_rq_nowait(struct request_queue *q, struct gendisk *bd_disk, @@ -72,7 +72,7 @@ EXPORT_SYMBOL_GPL(blk_execute_rq_nowait); * @at_head: insert request at head or tail of queue * * Description: - * Insert a fully prepared request at the back of the io scheduler queue + * Insert a fully prepared request at the back of the I/O scheduler queue * for execution and wait for completion. */ int blk_execute_rq(struct request_queue *q, struct gendisk *bd_disk, diff --git a/block/blk-integrity.c b/block/blk-integrity.c index 3f1a8478cc38..d87606eaca1d 100644 --- a/block/blk-integrity.c +++ b/block/blk-integrity.c @@ -109,8 +109,8 @@ EXPORT_SYMBOL(blk_rq_map_integrity_sg); /** * blk_integrity_compare - Compare integrity profile of two block devices - * @b1: Device to compare - * @b2: Device to compare + * @bd1: Device to compare + * @bd2: Device to compare * * Description: Meta-devices like DM and MD need to verify that all * sub-devices use the same integrity format before advertising to diff --git a/block/blk-map.c b/block/blk-map.c index af37e4ae62f5..ea1bf53929e4 100644 --- a/block/blk-map.c +++ b/block/blk-map.c @@ -85,17 +85,17 @@ static int __blk_rq_map_user(struct request_queue *q, struct request *rq, } /** - * blk_rq_map_user - map user data to a request, for REQ_BLOCK_PC usage + * blk_rq_map_user - map user data to a request, for REQ_TYPE_BLOCK_PC usage * @q: request queue where request should be inserted * @rq: request structure to fill * @ubuf: the user buffer * @len: length of user data * * Description: - * Data will be mapped directly for zero copy io, if possible. Otherwise + * Data will be mapped directly for zero copy I/O, if possible. Otherwise * a kernel bounce buffer is used. * - * A matching blk_rq_unmap_user() must be issued at the end of io, while + * A matching blk_rq_unmap_user() must be issued at the end of I/O, while * still in process context. * * Note: The mapped bio may need to be bounced through blk_queue_bounce() @@ -154,7 +154,7 @@ unmap_rq: EXPORT_SYMBOL(blk_rq_map_user); /** - * blk_rq_map_user_iov - map user data to a request, for REQ_BLOCK_PC usage + * blk_rq_map_user_iov - map user data to a request, for REQ_TYPE_BLOCK_PC usage * @q: request queue where request should be inserted * @rq: request to map data to * @iov: pointer to the iovec @@ -162,10 +162,10 @@ EXPORT_SYMBOL(blk_rq_map_user); * @len: I/O byte count * * Description: - * Data will be mapped directly for zero copy io, if possible. Otherwise + * Data will be mapped directly for zero copy I/O, if possible. Otherwise * a kernel bounce buffer is used. * - * A matching blk_rq_unmap_user() must be issued at the end of io, while + * A matching blk_rq_unmap_user() must be issued at the end of I/O, while * still in process context. * * Note: The mapped bio may need to be bounced through blk_queue_bounce() @@ -224,7 +224,7 @@ int blk_rq_map_user_iov(struct request_queue *q, struct request *rq, * Description: * Unmap a rq previously mapped by blk_rq_map_user(). The caller must * supply the original rq->bio from the blk_rq_map_user() return, since - * the io completion may have changed rq->bio. + * the I/O completion may have changed rq->bio. */ int blk_rq_unmap_user(struct bio *bio) { @@ -250,7 +250,7 @@ int blk_rq_unmap_user(struct bio *bio) EXPORT_SYMBOL(blk_rq_unmap_user); /** - * blk_rq_map_kern - map kernel data to a request, for REQ_BLOCK_PC usage + * blk_rq_map_kern - map kernel data to a request, for REQ_TYPE_BLOCK_PC usage * @q: request queue where request should be inserted * @rq: request to fill * @kbuf: the kernel buffer diff --git a/block/blk-settings.c b/block/blk-settings.c index 539d873c820d..d70692badcdb 100644 --- a/block/blk-settings.c +++ b/block/blk-settings.c @@ -144,7 +144,7 @@ EXPORT_SYMBOL(blk_queue_make_request); * Different hardware can have different requirements as to what pages * it can do I/O directly to. A low level driver can call * blk_queue_bounce_limit to have lower memory pages allocated as bounce - * buffers for doing I/O to pages residing above @page. + * buffers for doing I/O to pages residing above @dma_addr. **/ void blk_queue_bounce_limit(struct request_queue *q, u64 dma_addr) { @@ -229,7 +229,7 @@ EXPORT_SYMBOL(blk_queue_max_phys_segments); * Description: * Enables a low level driver to set an upper limit on the number of * hw data segments in a request. This would be the largest number of - * address/length pairs the host adapter can actually give as once + * address/length pairs the host adapter can actually give at once * to the device. **/ void blk_queue_max_hw_segments(struct request_queue *q, @@ -410,7 +410,7 @@ EXPORT_SYMBOL(blk_queue_segment_boundary); * @mask: alignment mask * * description: - * set required memory and length aligment for direct dma transactions. + * set required memory and length alignment for direct dma transactions. * this is used when buiding direct io requests for the queue. * **/ @@ -426,7 +426,7 @@ EXPORT_SYMBOL(blk_queue_dma_alignment); * @mask: alignment mask * * description: - * update required memory and length aligment for direct dma transactions. + * update required memory and length alignment for direct dma transactions. * If the requested alignment is larger than the current alignment, then * the current queue alignment is updated to the new value, otherwise it * is left alone. The design of this is to allow multiple objects diff --git a/block/blk-tag.c b/block/blk-tag.c index ed5166fbc599..8a99688eb1b1 100644 --- a/block/blk-tag.c +++ b/block/blk-tag.c @@ -29,7 +29,7 @@ EXPORT_SYMBOL(blk_queue_find_tag); * __blk_free_tags - release a given set of tag maintenance info * @bqt: the tag map to free * - * Tries to free the specified @bqt@. Returns true if it was + * Tries to free the specified @bqt. Returns true if it was * actually freed and false if there are still references using it */ static int __blk_free_tags(struct blk_queue_tag *bqt) @@ -78,7 +78,7 @@ void __blk_queue_free_tags(struct request_queue *q) * blk_free_tags - release a given set of tag maintenance info * @bqt: the tag map to free * - * For externally managed @bqt@ frees the map. Callers of this + * For externally managed @bqt frees the map. Callers of this * function must guarantee to have released all the queues that * might have been using this tag map. */ @@ -94,7 +94,7 @@ EXPORT_SYMBOL(blk_free_tags); * @q: the request queue for the device * * Notes: - * This is used to disabled tagged queuing to a device, yet leave + * This is used to disable tagged queuing to a device, yet leave * queue in function. **/ void blk_queue_free_tags(struct request_queue *q) @@ -271,7 +271,7 @@ EXPORT_SYMBOL(blk_queue_resize_tags); * @rq: the request that has completed * * Description: - * Typically called when end_that_request_first() returns 0, meaning + * Typically called when end_that_request_first() returns %0, meaning * all transfers have been done for a request. It's important to call * this function before end_that_request_last(), as that will put the * request back on the free list thus corrupting the internal tag list. diff --git a/block/genhd.c b/block/genhd.c index e0ce23ac2ece..c114a43052de 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -211,10 +211,11 @@ void unlink_gendisk(struct gendisk *disk) /** * get_gendisk - get partitioning information for a given device - * @dev: device to get partitioning information for + * @devt: device to get partitioning information for + * @part: returned partition index * * This function gets the structure containing partitioning - * information for the given device @dev. + * information for the given device @devt. */ struct gendisk *get_gendisk(dev_t devt, int *part) { -- cgit v1.2.3-58-ga151 From 79eb014578b79fcfb9d9e7dc979d1316079220aa Mon Sep 17 00:00:00 2001 From: FUJITA Tomonori Date: Thu, 18 Sep 2008 09:35:28 -0700 Subject: fix an example of scatterlists handling in DMA-API.txt This example isn't the proper way to handle scatterlists (can't handle sg chaining). Signed-off-by: FUJITA Tomonori Signed-off-by: Jens Axboe --- Documentation/DMA-API.txt | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'Documentation') diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt index d8b63d164e41..b8e86460046e 100644 --- a/Documentation/DMA-API.txt +++ b/Documentation/DMA-API.txt @@ -337,7 +337,7 @@ With scatterlists, you use the resulting mapping like this: int i, count = dma_map_sg(dev, sglist, nents, direction); struct scatterlist *sg; - for (i = 0, sg = sglist; i < count; i++, sg++) { + for_each_sg(sglist, sg, count, i) { hw_address[i] = sg_dma_address(sg); hw_len[i] = sg_dma_len(sg); } -- cgit v1.2.3-58-ga151 From b911e473d24633c19414b54b82b9ff0b1a2419d7 Mon Sep 17 00:00:00 2001 From: Randy Dunlap Date: Fri, 10 Oct 2008 08:22:44 +0200 Subject: doc/cdrom: Trvial documentation error, file not present The sbpcd tester program is not included in the kernel source tree, so remove the reference to it. Signed-off-by: Randy Dunlap Reported-by: Nick Warne Signed-off-by: Jens Axboe --- Documentation/cdrom/ide-cd | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'Documentation') diff --git a/Documentation/cdrom/ide-cd b/Documentation/cdrom/ide-cd index 91c0dcc6fa5c..2c558cd6c1ef 100644 --- a/Documentation/cdrom/ide-cd +++ b/Documentation/cdrom/ide-cd @@ -145,8 +145,7 @@ useful for reading photocds. To play an audio CD, you should first unmount and remove any data CDROM. Any of the CDROM player programs should then work (workman, -workbone, cdplayer, etc.). Lacking anything else, you could use the -cdtester program in Documentation/cdrom/sbpcd. +workbone, cdplayer, etc.). On a few drives, you can read digital audio directly using a program such as cdda2wav. The only types of drive which I've heard support -- cgit v1.2.3-58-ga151