On Thu, Jan 22, 2015 at 06:35:53PM +0300, Stefan Strogin wrote: > Hello Joonsoo, > > On 30/12/14 07:38, Joonsoo Kim wrote: > > On Fri, Dec 26, 2014 at 05:39:03PM +0300, Stefan I. Strogin wrote: > >> /proc/cmainfo contains a list of currently allocated CMA buffers for every > >> CMA area when CONFIG_CMA_DEBUG is enabled. > > Hello, > > > > I think that providing these information looks useful, but, we need better > > implementation. As Laura said, it is better to use debugfs. And, > > instead of re-implementing the wheel, how about using tracepoint > > to print these information? See below comments. > > Excuse me for a long delay. I've tried to give a detailed answer here: > https://lkml.org/lkml/2015/1/21/362 > Do you mean by «the re-implemented wheel» seq_print_stack_trace()? If so > then it was thought to show an owner of each allocated buffer. I used a > similar way as in page_owner: saving stack_trace for each allocation. Do > you think we can use tracepoints instead? I wrote why I said this is re-implemented wheel on the reply of other mail. Please refer it. Thanks. > > > > > >> Format is: > >> > >> <base_phys_addr> - <end_phys_addr> (<size> kB), allocated by <PID>\ > >> (<command name>), latency <allocation latency> us > >> <stack backtrace when the buffer had been allocated> > >> > >> Signed-off-by: Stefan I. Strogin <s.strogin@xxxxxxxxxxxxxxxxxxx> > >> --- > >> mm/cma.c | 202 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > >> 1 file changed, 202 insertions(+) > >> > >> diff --git a/mm/cma.c b/mm/cma.c > >> index a85ae28..ffaea26 100644 > >> --- a/mm/cma.c > >> +++ b/mm/cma.c > >> @@ -34,6 +34,10 @@ > >> #include <linux/cma.h> > >> #include <linux/highmem.h> > >> #include <linux/io.h> > >> +#include <linux/list.h> > >> +#include <linux/proc_fs.h> > >> +#include <linux/uaccess.h> > >> +#include <linux/time.h> > >> > >> struct cma { > >> unsigned long base_pfn; > >> @@ -41,8 +45,25 @@ struct cma { > >> unsigned long *bitmap; > >> unsigned int order_per_bit; /* Order of pages represented by one bit */ > >> struct mutex lock; > >> +#ifdef CONFIG_CMA_DEBUG > >> + struct list_head buffers_list; > >> + struct mutex list_lock; > >> +#endif > >> }; > >> > >> +#ifdef CONFIG_CMA_DEBUG > >> +struct cma_buffer { > >> + unsigned long pfn; > >> + unsigned long count; > >> + pid_t pid; > >> + char comm[TASK_COMM_LEN]; > >> + unsigned int latency; > >> + unsigned long trace_entries[16]; > >> + unsigned int nr_entries; > >> + struct list_head list; > >> +}; > >> +#endif > >> + > >> static struct cma cma_areas[MAX_CMA_AREAS]; > >> static unsigned cma_area_count; > >> static DEFINE_MUTEX(cma_mutex); > >> @@ -132,6 +153,10 @@ static int __init cma_activate_area(struct cma *cma) > >> } while (--i); > >> > >> mutex_init(&cma->lock); > >> +#ifdef CONFIG_CMA_DEBUG > >> + INIT_LIST_HEAD(&cma->buffers_list); > >> + mutex_init(&cma->list_lock); > >> +#endif > >> return 0; > >> > >> err: > >> @@ -347,6 +372,86 @@ err: > >> return ret; > >> } > >> > >> +#ifdef CONFIG_CMA_DEBUG > >> +/** > >> + * cma_buffer_list_add() - add a new entry to a list of allocated buffers > >> + * @cma: Contiguous memory region for which the allocation is performed. > >> + * @pfn: Base PFN of the allocated buffer. > >> + * @count: Number of allocated pages. > >> + * @latency: Nanoseconds spent to allocate the buffer. > >> + * > >> + * This function adds a new entry to the list of allocated contiguous memory > >> + * buffers in a CMA area. It uses the CMA area specificated by the device > >> + * if available or the default global one otherwise. > >> + */ > >> +static int cma_buffer_list_add(struct cma *cma, unsigned long pfn, > >> + int count, s64 latency) > >> +{ > >> + struct cma_buffer *cmabuf; > >> + struct stack_trace trace; > >> + > >> + cmabuf = kmalloc(sizeof(struct cma_buffer), GFP_KERNEL); > >> + if (!cmabuf) > >> + return -ENOMEM; > >> + > >> + trace.nr_entries = 0; > >> + trace.max_entries = ARRAY_SIZE(cmabuf->trace_entries); > >> + trace.entries = &cmabuf->trace_entries[0]; > >> + trace.skip = 2; > >> + save_stack_trace(&trace); > >> + > >> + cmabuf->pfn = pfn; > >> + cmabuf->count = count; > >> + cmabuf->pid = task_pid_nr(current); > >> + cmabuf->nr_entries = trace.nr_entries; > >> + get_task_comm(cmabuf->comm, current); > >> + cmabuf->latency = (unsigned int) div_s64(latency, NSEC_PER_USEC); > >> + > >> + mutex_lock(&cma->list_lock); > >> + list_add_tail(&cmabuf->list, &cma->buffers_list); > >> + mutex_unlock(&cma->list_lock); > >> + > >> + return 0; > >> +} > >> + > >> +/** > >> + * cma_buffer_list_del() - delete an entry from a list of allocated buffers > >> + * @cma: Contiguous memory region for which the allocation was performed. > >> + * @pfn: Base PFN of the released buffer. > >> + * > >> + * This function deletes a list entry added by cma_buffer_list_add(). > >> + */ > >> +static void cma_buffer_list_del(struct cma *cma, unsigned long pfn) > >> +{ > >> + struct cma_buffer *cmabuf; > >> + > >> + mutex_lock(&cma->list_lock); > >> + > >> + list_for_each_entry(cmabuf, &cma->buffers_list, list) > >> + if (cmabuf->pfn == pfn) { > >> + list_del(&cmabuf->list); > >> + kfree(cmabuf); > >> + goto out; > >> + } > >> + > > Is there more elegant way to find buffer? This linear search overhead > > would change system behaviour if there are lots of buffers. > > > >> + pr_err("%s(pfn %lu): couldn't find buffers list entry\n", > >> + __func__, pfn); > >> + > >> +out: > >> + mutex_unlock(&cma->list_lock); > >> +} > >> +#else > >> +static int cma_buffer_list_add(struct cma *cma, unsigned long pfn, > >> + int count, s64 latency) > >> +{ > >> + return 0; > >> +} > >> + > >> +static void cma_buffer_list_del(struct cma *cma, unsigned long pfn) > >> +{ > >> +} > >> +#endif /* CONFIG_CMA_DEBUG */ > >> + > >> /** > >> * cma_alloc() - allocate pages from contiguous area > >> * @cma: Contiguous memory region for which the allocation is performed. > >> @@ -361,11 +466,15 @@ struct page *cma_alloc(struct cma *cma, int count, unsigned int align) > >> unsigned long mask, offset, pfn, start = 0; > >> unsigned long bitmap_maxno, bitmap_no, bitmap_count; > >> struct page *page = NULL; > >> + struct timespec ts1, ts2; > >> + s64 latency; > >> int ret; > >> > >> if (!cma || !cma->count) > >> return NULL; > >> > >> + getnstimeofday(&ts1); > >> + > >> pr_debug("%s(cma %p, count %d, align %d)\n", __func__, (void *)cma, > >> count, align); > >> > >> @@ -413,6 +522,19 @@ struct page *cma_alloc(struct cma *cma, int count, unsigned int align) > >> start = bitmap_no + mask + 1; > >> } > >> > >> + getnstimeofday(&ts2); > >> + latency = timespec_to_ns(&ts2) - timespec_to_ns(&ts1); > >> + > >> + if (page) { > >> + ret = cma_buffer_list_add(cma, pfn, count, latency); > >> + if (ret) { > >> + pr_warn("%s(): cma_buffer_list_add() returned %d\n", > >> + __func__, ret); > >> + cma_release(cma, page, count); > >> + page = NULL; > >> + } > > So, we would fail to allocate CMA memory if we can't allocate buffer > > for debugging. I don't think it makes sense. With tracepoint, > > we don't need to allocate buffer in runtime. > > > > Thanks. > > > > -- > > To unsubscribe, send a message with 'unsubscribe linux-mm' in > > the body to majordomo@xxxxxxxxx. For more info on Linux MM, > > see: http://www.linux-mm.org/ . > > Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a> > > > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@xxxxxxxxx. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a> -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>