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path: root/include/linux/async_tx.h
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2009-09-08dmaengine: add fence supportDan Williams
Some engines optimize operation by reading ahead in the descriptor chain such that descriptor2 may start execution before descriptor1 completes. If descriptor2 depends on the result from descriptor1 then a fence is required (on descriptor2) to disable this optimization. The async_tx api could implicitly identify dependencies via the 'depend_tx' parameter, but that would constrain cases where the dependency chain only specifies a completion order rather than a data dependency. So, provide an ASYNC_TX_FENCE to explicitly identify data dependencies. Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2009-08-29async_tx: add support for asynchronous RAID6 recovery operationsDan Williams
async_raid6_2data_recov() recovers two data disk failures async_raid6_datap_recov() recovers a data disk and the P disk These routines are a port of the synchronous versions found in drivers/md/raid6recov.c. The primary difference is breaking out the xor operations into separate calls to async_xor. Two helper routines are introduced to perform scalar multiplication where needed. async_sum_product() multiplies two sources by scalar coefficients and then sums (xor) the result. async_mult() simply multiplies a single source by a scalar. This implemention also includes, in contrast to the original synchronous-only code, special case handling for the 4-disk and 5-disk array cases. In these situations the default N-disk algorithm will present 0-source or 1-source operations to dma devices. To cover for dma devices where the minimum source count is 2 we implement 4-disk and 5-disk handling in the recovery code. [ Impact: asynchronous raid6 recovery routines for 2data and datap cases ] Cc: Yuri Tikhonov <yur@emcraft.com> Cc: Ilya Yanok <yanok@emcraft.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: David Woodhouse <David.Woodhouse@intel.com> Reviewed-by: Andre Noll <maan@systemlinux.org> Acked-by: Maciej Sosnowski <maciej.sosnowski@intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2009-08-29async_tx: add support for asynchronous GF multiplicationDan Williams
[ Based on an original patch by Yuri Tikhonov ] This adds support for doing asynchronous GF multiplication by adding two additional functions to the async_tx API: async_gen_syndrome() does simultaneous XOR and Galois field multiplication of sources. async_syndrome_val() validates the given source buffers against known P and Q values. When a request is made to run async_pq against more than the hardware maximum number of supported sources we need to reuse the previous generated P and Q values as sources into the next operation. Care must be taken to remove Q from P' and P from Q'. For example to perform a 5 source pq op with hardware that only supports 4 sources at a time the following approach is taken: p, q = PQ(src0, src1, src2, src3, COEF({01}, {02}, {04}, {08})) p', q' = PQ(p, q, q, src4, COEF({00}, {01}, {00}, {10})) p' = p + q + q + src4 = p + src4 q' = {00}*p + {01}*q + {00}*q + {10}*src4 = q + {10}*src4 Note: 4 is the minimum acceptable maxpq otherwise we punt to synchronous-software path. The DMA_PREP_CONTINUE flag indicates to the driver to reuse p and q as sources (in the above manner) and fill the remaining slots up to maxpq with the new sources/coefficients. Note1: Some devices have native support for P+Q continuation and can skip this extra work. Devices with this capability can advertise it with dma_set_maxpq. It is up to each driver how to handle the DMA_PREP_CONTINUE flag. Note2: The api supports disabling the generation of P when generating Q, this is ignored by the synchronous path but is implemented by some dma devices to save unnecessary writes. In this case the continuation algorithm is simplified to only reuse Q as a source. Cc: H. Peter Anvin <hpa@zytor.com> Cc: David Woodhouse <David.Woodhouse@intel.com> Signed-off-by: Yuri Tikhonov <yur@emcraft.com> Signed-off-by: Ilya Yanok <yanok@emcraft.com> Reviewed-by: Andre Noll <maan@systemlinux.org> Acked-by: Maciej Sosnowski <maciej.sosnowski@intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2009-08-29async_tx: remove walk of tx->parent chain in dma_wait_for_async_txDan Williams
We currently walk the parent chain when waiting for a given tx to complete however this walk may race with the driver cleanup routine. The routines in async_raid6_recov.c may fall back to the synchronous path at any point so we need to be prepared to call async_tx_quiesce() (which calls dma_wait_for_async_tx). To remove the ->parent walk we guarantee that every time a dependency is attached ->issue_pending() is invoked, then we can simply poll the initial descriptor until completion. This also allows for a lighter weight 'issue pending' implementation as there is no longer a requirement to iterate through all the channels' ->issue_pending() routines as long as operations have been submitted in an ordered chain. async_tx_issue_pending() is added for this case. Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2009-08-29async_tx: add sum check flagsDan Williams
Replace the flat zero_sum_result with a collection of flags to contain the P (xor) zero-sum result, and the soon to be utilized Q (raid6 reed solomon syndrome) zero-sum result. Use the SUM_CHECK_ namespace instead of DMA_ since these flags will be used on non-dma-zero-sum enabled platforms. Reviewed-by: Andre Noll <maan@systemlinux.org> Acked-by: Maciej Sosnowski <maciej.sosnowski@intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2009-06-03async_tx: structify submission arguments, add scribbleDan Williams
Prepare the api for the arrival of a new parameter, 'scribble'. This will allow callers to identify scratchpad memory for dma address or page address conversions. As this adds yet another parameter, take this opportunity to convert the common submission parameters (flags, dependency, callback, and callback argument) into an object that is passed by reference. Also, take this opportunity to fix up the kerneldoc and add notes about the relevant ASYNC_TX_* flags for each routine. [ Impact: moves api pass-by-value parameters to a pass-by-reference struct ] Signed-off-by: Andre Noll <maan@systemlinux.org> Acked-by: Maciej Sosnowski <maciej.sosnowski@intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2009-06-03async_tx: kill ASYNC_TX_DEP_ACK flagDan Williams
In support of inter-channel chaining async_tx utilizes an ack flag to gate whether a dependent operation can be chained to another. While the flag is not set the chain can be considered open for appending. Setting the ack flag closes the chain and flags the descriptor for garbage collection. The ASYNC_TX_DEP_ACK flag essentially means "close the chain after adding this dependency". Since each operation can only have one child the api now implicitly sets the ack flag at dependency submission time. This removes an unnecessary management burden from clients of the api. [ Impact: clean up and enforce one dependency per operation ] Reviewed-by: Andre Noll <maan@systemlinux.org> Acked-by: Maciej Sosnowski <maciej.sosnowski@intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2009-04-08async_tx: rename zero_sum to valDan Williams
'zero_sum' does not properly describe the operation of generating parity and checking that it validates against an existing buffer. Change the name of the operation to 'val' (for 'validate'). This is in anticipation of the p+q case where it is a requirement to identify the target parity buffers separately from the source buffers, because the target parity buffers will not have corresponding pq coefficients. Reviewed-by: Andre Noll <maan@systemlinux.org> Acked-by: Maciej Sosnowski <maciej.sosnowski@intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2009-03-25async_tx: provide __async_inline for HAS_DMA=n archsDan Williams
To allow an async_tx routine to be compiled away on HAS_DMA=n arch it needs to be declared __always_inline otherwise the compiler may emit code and cause a link error. Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2009-01-06dmaengine: provide a common 'issue_pending_all' implementationDan Williams
async_tx and net_dma each have open-coded versions of issue_pending_all, so provide a common routine in dmaengine. The implementation needs to walk the global device list, so implement rcu to allow dma_issue_pending_all to run lockless. Clients protect themselves from channel removal events by holding a dmaengine reference. Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2009-01-05dmaengine: remove dependency on async_txDan Williams
async_tx.ko is a consumer of dma channels. A circular dependency arises if modules in drivers/dma rely on common code in async_tx.ko. It prevents either module from being unloaded. Move dma_wait_for_async_tx and async_tx_run_dependencies to dmaeninge.o where they should have been from the beginning. Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2008-07-17async_tx: remove depend_tx from async_tx_sync_epilogDan Williams
All callers of async_tx_sync_epilog have called async_tx_quiesce on the depend_tx, so async_tx_sync_epilog need only call the callback to complete the operation. Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2008-07-17async_tx: export async_tx_quiesceDan Williams
Replace open coded "wait and acknowledge" instances with async_tx_quiesce. Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2008-02-06async_tx: allow architecture specific async_tx_find_channel implementationsDan Williams
The source and destination addresses are included to allow channel selection based on address alignment. Signed-off-by: Dan Williams <dan.j.williams@intel.com> Reviewed-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
2008-02-06async_tx: kill ASYNC_TX_ASSUME_COHERENTDan Williams
Remove the unused ASYNC_TX_ASSUME_COHERENT flag. Async_tx is meant to hide the difference between asynchronous hardware and synchronous software operations, this flag requires clients to understand cache coherency consequences of the async path. Signed-off-by: Dan Williams <dan.j.williams@intel.com> Reviewed-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
2007-07-20async_tx: fix kmap_atomic usage in async_memcpyDan Williams
Andrew Morton: [async_memcpy] is very wrong if both ASYNC_TX_KMAP_DST and ASYNC_TX_KMAP_SRC can ever be set. We'll end up using the same kmap slot for both src add dest and we get either corrupted data or a BUG. Evgeniy Polyakov: Btw, shouldn't it always be kmap_atomic() even if flag is not set. That pages are usual one returned by alloc_page(). So fix the usage of kmap_atomic and kill the ASYNC_TX_KMAP_DST and ASYNC_TX_KMAP_SRC flags. Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Evgeniy Polyakov <johnpol@2ka.mipt.ru> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-13async_tx: add the async_tx apiDan Williams
The async_tx api provides methods for describing a chain of asynchronous bulk memory transfers/transforms with support for inter-transactional dependencies. It is implemented as a dmaengine client that smooths over the details of different hardware offload engine implementations. Code that is written to the api can optimize for asynchronous operation and the api will fit the chain of operations to the available offload resources. I imagine that any piece of ADMA hardware would register with the 'async_*' subsystem, and a call to async_X would be routed as appropriate, or be run in-line. - Neil Brown async_tx exploits the capabilities of struct dma_async_tx_descriptor to provide an api of the following general format: struct dma_async_tx_descriptor * async_<operation>(..., struct dma_async_tx_descriptor *depend_tx, dma_async_tx_callback cb_fn, void *cb_param) { struct dma_chan *chan = async_tx_find_channel(depend_tx, <operation>); struct dma_device *device = chan ? chan->device : NULL; int int_en = cb_fn ? 1 : 0; struct dma_async_tx_descriptor *tx = device ? device->device_prep_dma_<operation>(chan, len, int_en) : NULL; if (tx) { /* run <operation> asynchronously */ ... tx->tx_set_dest(addr, tx, index); ... tx->tx_set_src(addr, tx, index); ... async_tx_submit(chan, tx, flags, depend_tx, cb_fn, cb_param); } else { /* run <operation> synchronously */ ... <operation> ... async_tx_sync_epilog(flags, depend_tx, cb_fn, cb_param); } return tx; } async_tx_find_channel() returns a capable channel from its pool. The channel pool is organized as a per-cpu array of channel pointers. The async_tx_rebalance() routine is tasked with managing these arrays. In the uniprocessor case async_tx_rebalance() tries to spread responsibility evenly over channels of similar capabilities. For example if there are two copy+xor channels, one will handle copy operations and the other will handle xor. In the SMP case async_tx_rebalance() attempts to spread the operations evenly over the cpus, e.g. cpu0 gets copy channel0 and xor channel0 while cpu1 gets copy channel 1 and xor channel 1. When a dependency is specified async_tx_find_channel defaults to keeping the operation on the same channel. A xor->copy->xor chain will stay on one channel if it supports both operation types, otherwise the transaction will transition between a copy and a xor resource. Currently the raid5 implementation in the MD raid456 driver has been converted to the async_tx api. A driver for the offload engines on the Intel Xscale series of I/O processors, iop-adma, is provided in a later commit. With the iop-adma driver and async_tx, raid456 is able to offload copy, xor, and xor-zero-sum operations to hardware engines. On iop342 tiobench showed higher throughput for sequential writes (20 - 30% improvement) and sequential reads to a degraded array (40 - 55% improvement). For the other cases performance was roughly equal, +/- a few percentage points. On a x86-smp platform the performance of the async_tx implementation (in synchronous mode) was also +/- a few percentage points of the original implementation. According to 'top' on iop342 CPU utilization drops from ~50% to ~15% during a 'resync' while the speed according to /proc/mdstat doubles from ~25 MB/s to ~50 MB/s. The tiobench command line used for testing was: tiobench --size 2048 --block 4096 --block 131072 --dir /mnt/raid --numruns 5 * iop342 had 1GB of memory available Details: * if CONFIG_DMA_ENGINE=n the asynchronous path is compiled away by making async_tx_find_channel a static inline routine that always returns NULL * when a callback is specified for a given transaction an interrupt will fire at operation completion time and the callback will occur in a tasklet. if the the channel does not support interrupts then a live polling wait will be performed * the api is written as a dmaengine client that requests all available channels * In support of dependencies the api implicitly schedules channel-switch interrupts. The interrupt triggers the cleanup tasklet which causes pending operations to be scheduled on the next channel * Xor engines treat an xor destination address differently than a software xor routine. To the software routine the destination address is an implied source, whereas engines treat it as a write-only destination. This patch modifies the xor_blocks routine to take a an explicit destination address to mirror the hardware. Changelog: * fixed a leftover debug print * don't allow callbacks in async_interrupt_cond * fixed xor_block changes * fixed usage of ASYNC_TX_XOR_DROP_DEST * drop dma mapping methods, suggested by Chris Leech * printk warning fixups from Andrew Morton * don't use inline in C files, Adrian Bunk * select the API when MD is enabled * BUG_ON xor source counts <= 1 * implicitly handle hardware concerns like channel switching and interrupts, Neil Brown * remove the per operation type list, and distribute operation capabilities evenly amongst the available channels * simplify async_tx_find_channel to optimize the fast path * introduce the channel_table_initialized flag to prevent early calls to the api * reorganize the code to mimic crypto * include mm.h as not all archs include it in dma-mapping.h * make the Kconfig options non-user visible, Adrian Bunk * move async_tx under crypto since it is meant as 'core' functionality, and the two may share algorithms in the future * move large inline functions into c files * checkpatch.pl fixes * gpl v2 only correction Cc: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Acked-By: NeilBrown <neilb@suse.de>