On 2016/2/23 17:32, Shawn Lin wrote: > On 2016/2/23 15:02, He YunLei wrote: >> On 2016/2/23 13:44, Chao Yu wrote: >>> Hi Yunlei, >> Hi Chao, >>> >>>> -----Original Message----- >>>> From: Yunlei He [mailto:heyun...@huawei.com] >>>> Sent: Tuesday, February 23, 2016 12:08 PM >>>> To: chao2...@samsung.com; jaeg...@kernel.org; >>>> linux-f2fs-devel@lists.sourceforge.net >>>> Cc: bintian.w...@huawei.com; Yunlei He; Biao He >>>> Subject: [f2fs-dev] [PATCH] f2fs: avoid hungtask problem caused by losing >>>> wake_up >>>> >>>> The D state of wait_on_all_pages_writeback should be waken by >>>> function f2fs_write_end_io when all writeback pages have been >>>> succesfully written to device. It's possible that wake_up comes >>>> between get_pages and io_schedule. Maybe in this case it will >>>> lost wake_up and still in D state even if all pages have been >>>> write back to device, and finally, the whole system will be into >>>> the hungtask state. >>> >>> I haven't encountered such issue so far, do you suffer this in real >>> world? >>> >> yes, I have encounter it, the whole file system is blocked at function >> wait_on_all_pages_writeback beyond 120s when write cp, and no error reported >> by storage device driver. > Hi Shawn, > Hi YunLei > > Interesting... > How to prove the page isn't been locked by storage block layer which > doesn't finish the related bio? > > I suffer that case before, but then I solve it by seting a timer to > break my mmc driver while missing some important interrupts(chip > problem) for data-transfer to finish the io queue by mmcqd. > Thanks for your review, I has replied Chao about the info of f2fs_sb_info, and from the info we can make sure the block layer and device driver are both ok.
> Another thing, > why making 5HZ for timeout? why not 10HZ ,15HZ... > io_schedule_timeout(5*HZ); > We choose 5HZ in our test, maybe other value is more reasonable. >>>> >>>> if (!get_pages(sbi, F2FS_WRITEBACK)) >>>> break; >>>> <--------- wake_up >>> >>> wake_up will put all tasks linked in sbi->cp_wait on run-queue, so >>> here it should be save to call io_schedule, after being rescheduled, >>> it will get the chance to check above condition to break out. >>> >>> Thanks, >> >> Here, we just doubt something weird may cause wait_on_all_pages_writeback >> could not be waken. Wake_up trigger only one time by last bio's end_io >> function, if the thread happen to miss it, the thread will be in D state >> forever. So we change the code to make wait_on_all_pages_writeback awaken >> periodically, then check the condition. >> >>> >>>> io_schedule(); >>>> >>>> Signed-off-by: Yunlei He <heyun...@huawei.com> >>>> Signed-off-by: Biao He <hebi...@huawei.com> >>>> --- >>>> fs/f2fs/checkpoint.c | 2 +- >>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>> >>>> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c >>>> index 2bac8a1..f55355d 100644 >>>> --- a/fs/f2fs/checkpoint.c >>>> +++ b/fs/f2fs/checkpoint.c >>>> @@ -920,7 +920,7 @@ static void wait_on_all_pages_writeback(struct >>>> f2fs_sb_info *sbi) >>>> if (!get_pages(sbi, F2FS_WRITEBACK)) >>>> break; >>>> >>>> - io_schedule(); >>>> + io_schedule_timeout(5*HZ); >>>> } >>>> finish_wait(&sbi->cp_wait, &wait); >>>> } >>>> -- >>>> 1.9.1 >>> >>> >>> >>> . >>> >> >> >> ------------------------------------------------------------------------------ >> Site24x7 APM Insight: Get Deep Visibility into Application Performance >> APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month >> Monitor end-to-end web transactions and take corrective actions now >> Troubleshoot faster and improve end-user experience. Signup Now! >> http://pubads.g.doubleclick.net/gampad/clk?id=272487151&iu=/4140 >> _______________________________________________ >> Linux-f2fs-devel mailing list >> Linux-f2fs-devel@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel >> > > > . > ------------------------------------------------------------------------------ Site24x7 APM Insight: Get Deep Visibility into Application Performance APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month Monitor end-to-end web transactions and take corrective actions now Troubleshoot faster and improve end-user experience. Signup Now! http://pubads.g.doubleclick.net/gampad/clk?id=272487151&iu=/4140 _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
