From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f45.google.com (mail-pa0-f45.google.com [209.85.220.45]) by kanga.kvack.org (Postfix) with ESMTP id 9F52D6B0073 for ; Thu, 22 Jan 2015 10:36:01 -0500 (EST) Received: by mail-pa0-f45.google.com with SMTP id lf10so2480511pab.4 for ; Thu, 22 Jan 2015 07:36:01 -0800 (PST) Received: from mailout2.w1.samsung.com (mailout2.w1.samsung.com. [210.118.77.12]) by mx.google.com with ESMTPS id xe5si12741963pab.185.2015.01.22.07.35.59 for (version=TLSv1 cipher=RC4-MD5 bits=128/128); Thu, 22 Jan 2015 07:36:00 -0800 (PST) MIME-version: 1.0 Content-type: text/plain; charset=windows-1252 Received: from eucpsbgm2.samsung.com (unknown [203.254.199.245]) by mailout2.w1.samsung.com (Oracle Communications Messaging Server 7u4-24.01(7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTP id <0NIL00B5X4UNPF60@mailout2.w1.samsung.com> for linux-mm@kvack.org; Thu, 22 Jan 2015 15:39:59 +0000 (GMT) Content-transfer-encoding: 8BIT Message-id: <54C118D9.9040007@partner.samsung.com> Date: Thu, 22 Jan 2015 18:35:53 +0300 From: Stefan Strogin Subject: Re: [PATCH 2/3] mm: cma: introduce /proc/cmainfo References: <264ce8ad192124f2afec9a71a2fc28779d453ba7.1419602920.git.s.strogin@partner.samsung.com> <20141230043814.GB4588@js1304-P5Q-DELUXE> In-reply-to: <20141230043814.GB4588@js1304-P5Q-DELUXE> Sender: owner-linux-mm@kvack.org List-ID: To: Joonsoo Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Marek Szyprowski , Michal Nazarewicz , aneesh.kumar@linux.vnet.ibm.com, Laurent Pinchart , Dmitry Safonov , Pintu Kumar , Weijie Yang , Laura Abbott , SeongJae Park , Hui Zhu , Minchan Kim , Dyasly Sergey , Vyacheslav Tyrtov 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 <> 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? > >> Format is: >> >> - ( kB), allocated by \ >> (), latency us >> >> >> Signed-off-by: Stefan I. Strogin >> --- >> 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 >> #include >> #include >> +#include >> +#include >> +#include >> +#include >> >> 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@kvack.org. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: email@kvack.org > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org