Date: Fri, 2 Dec 2016 12:53:02 +0800 From: Sepherosa Ziehau <sepherosa@gmail.com> To: John Baldwin <jhb@freebsd.org> Cc: "freebsd-current@freebsd.org" <current@freebsd.org> Subject: Re: Please test EARLY_AP_STARTUP Message-ID: <CAMOc5cyGLOcfNp%2Bwn3o16FCEggci2wyr6eCN==npfnUU1ThZJA@mail.gmail.com> In-Reply-To: <2914745.0k996KCSkq@ralph.baldwin.cx> References: <7005233.xZtqgRZ2t6@ralph.baldwin.cx> <CAMOc5cz_KzkJnh-QDTWhpr%2BF0nOPcp9YF3YLseUJ=qQQvW_-EA@mail.gmail.com> <CAMOc5cxkRK5dw4R2gHhvOX4rnR%2BadKCm0XcaReZL5s=Mw-%2Baaw@mail.gmail.com> <2914745.0k996KCSkq@ralph.baldwin.cx>
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On Fri, Dec 2, 2016 at 1:49 AM, John Baldwin <jhb@freebsd.org> wrote: > On Thursday, December 01, 2016 01:53:29 PM Sepherosa Ziehau wrote: >> On Wed, Nov 30, 2016 at 9:59 AM, Sepherosa Ziehau <sepherosa@gmail.com> wrote: >> >>> After fdc is disabled and hyperv/storvsc is fixed, it seems to boot >> >>> fine, except a long delay (28~30seconds) here: >> >>> .... >> >>> Timecounters tick every 1.000 msec >> >>> ----- >> >>> 28 ~ 30 seconds delay >> >>> ----- >> >>> vlan: initialized, using hash tables with chaining >> >>> .... >> >>> >> >>> I have the bootverbose dmesg here: >> >>> https://people.freebsd.org/~sephe/dmesg_earlyap.txt >> >>> >> >>> I booted 10 times, only one boot does not suffer this 30 seconds >> >>> delay. It sounds like some races to me. Any hints? >> >> >> >> It is likely a race as we start running things sooner now, yes. Can you >> >> break into DDB during the hang and see what thread0 is waiting on? If >> >> it is in the interrupt hooks you can use 'show conifhk' in DDB to see the >> >> list of pending interrupt hooks. That provides a list of candidate drivers >> >> to inspect (e.g. stack traces of relevant kthreads) for what is actually >> >> waiting (and what it is waiting on) >> > >> > Just tried, but I failed to break into DDB during the 30 seconds >> > delay. DDB was entered after the 30 seconds delay, though I press the >> > break key when the delay started. >> >> I tried add VERBOSE_SYSINIT option in order to get a rough location of >> this delay, but the system boots just fine w/ VERBOSE_SYSINIT option, >> sigh. > > You could add KTR_PROC tracing and use 'show ktr' in DDB when you break in after the > 30 second delay to see what it was doing during the delay perhaps? I have narrowed it down by patching the VERBOSE_SYSINIT: the kthread_start(&deadlkres_kd) introduces the 30 seconds delay, i.e. SYSINIT(deadlkres, SI_SUB_CLOCKS, SI_ORDER_ANY, kthread_start, &deadlkres_kd) blocks for 30 seconds. Thanks, sephe -- Tomorrow Will Never Die
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