Messages in this thread | | | Date | Mon, 12 Nov 2012 10:48:02 +0100 | From | Soeren Moch <> | Subject | Re: [PATCH] mm: dmapool: use provided gfp flags for all dma_alloc_coherent() calls |
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On 11.11.2012 18:22, Andrew Lunn wrote: > On Thu, Nov 08, 2012 at 07:38:57AM +0100, Marek Szyprowski wrote: >> dmapool always calls dma_alloc_coherent() with GFP_ATOMIC flag, regardless >> the flags provided by the caller. This causes excessive pruning of >> emergency memory pools without any good reason. This patch changes the code >> to correctly use gfp flags provided by the dmapool caller. This should >> solve the dmapool usage on ARM architecture, where GFP_ATOMIC DMA >> allocations can be served only from the special, very limited memory pool. >> >> Reported-by: Soren Moch <smoch@web.de> Please use Reported-by: Soeren Moch <smoch@web.de>
>> Reported-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com> >> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> > > Tested-by: Andrew Lunn <andrew@lunn.ch> > > I tested this on a Kirkwood QNAP after removing the call to > init_dma_coherent_pool_size(). > > Andrew
Tested-by: Soeren Moch <smoch@web.de>
Now I had a chance to test this patch on my Kirkwood guruplug system with linux-3.6.6 . It is running much better now, but with the original 256K coherent pool size I still see errors after several hours of runtime:
Nov 12 09:42:32 guru kernel: ERROR: 256 KiB atomic DMA coherent pool is too small! Nov 12 09:42:32 guru kernel: Please increase it with coherent_pool= kernel parameter!
Soeren
>> --- >> mm/dmapool.c | 27 +++++++-------------------- >> 1 file changed, 7 insertions(+), 20 deletions(-) >> >> diff --git a/mm/dmapool.c b/mm/dmapool.c >> index c5ab33b..86de9b2 100644 >> --- a/mm/dmapool.c >> +++ b/mm/dmapool.c >> @@ -62,8 +62,6 @@ struct dma_page { /* cacheable header for 'allocation' bytes */ >> unsigned int offset; >> }; >> >> -#define POOL_TIMEOUT_JIFFIES ((100 /* msec */ * HZ) / 1000) >> - >> static DEFINE_MUTEX(pools_lock); >> >> static ssize_t >> @@ -227,7 +225,6 @@ static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags) >> memset(page->vaddr, POOL_POISON_FREED, pool->allocation); >> #endif >> pool_initialise_page(pool, page); >> - list_add(&page->page_list, &pool->page_list); >> page->in_use = 0; >> page->offset = 0; >> } else { >> @@ -315,30 +312,21 @@ void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags, >> might_sleep_if(mem_flags & __GFP_WAIT); >> >> spin_lock_irqsave(&pool->lock, flags); >> - restart: >> list_for_each_entry(page, &pool->page_list, page_list) { >> if (page->offset < pool->allocation) >> goto ready; >> } >> - page = pool_alloc_page(pool, GFP_ATOMIC); >> - if (!page) { >> - if (mem_flags & __GFP_WAIT) { >> - DECLARE_WAITQUEUE(wait, current); >> >> - __set_current_state(TASK_UNINTERRUPTIBLE); >> - __add_wait_queue(&pool->waitq, &wait); >> - spin_unlock_irqrestore(&pool->lock, flags); >> + /* pool_alloc_page() might sleep, so temporarily drop &pool->lock */ >> + spin_unlock_irqrestore(&pool->lock, flags); >> >> - schedule_timeout(POOL_TIMEOUT_JIFFIES); >> + page = pool_alloc_page(pool, mem_flags); >> + if (!page) >> + return NULL; >> >> - spin_lock_irqsave(&pool->lock, flags); >> - __remove_wait_queue(&pool->waitq, &wait); >> - goto restart; >> - } >> - retval = NULL; >> - goto done; >> - } >> + spin_lock_irqsave(&pool->lock, flags); >> >> + list_add(&page->page_list, &pool->page_list); >> ready: >> page->in_use++; >> offset = page->offset; >> @@ -348,7 +336,6 @@ void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags, >> #ifdef DMAPOOL_DEBUG >> memset(retval, POOL_POISON_ALLOCATED, pool->size); >> #endif >> - done: >> spin_unlock_irqrestore(&pool->lock, flags); >> return retval; >> } >> -- >> 1.7.9.5 >>
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