Date: Thu, 20 Sep 2012 14:04:22 +0300 From: Andriy Gapon <avg@FreeBSD.org> To: attilio@FreeBSD.org Cc: freebsd-hackers <freebsd-hackers@FreeBSD.org>, Jeff Roberson <jeff@FreeBSD.org> Subject: Re: ule+smp: small optimization for turnstile priority lending Message-ID: <505AF836.7050004@FreeBSD.org> In-Reply-To: <CAJ-FndBxWYOkRCn-DZTdZ%2BB4RpvsvaxtwDyMc8M7YhRj9DaL2w@mail.gmail.com> References: <50587F8D.9060102@FreeBSD.org> <CAJ-FndCWzTBRYsA0mFDCj8RU06ZUTi3G0LeEFcS9_c5zKd%2BgWQ@mail.gmail.com> <5058C68B.1010508@FreeBSD.org> <CAJ-FndC8j12a95N0QprYTLJLC06R8jjcaHuxEZKu5D9RHW=ZVw@mail.gmail.com> <50596019.5060708@FreeBSD.org> <CAJ-FndBxWYOkRCn-DZTdZ%2BB4RpvsvaxtwDyMc8M7YhRj9DaL2w@mail.gmail.com>
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on 19/09/2012 10:33 Attilio Rao said the following: > It is hard for me to tell if this is subject to same issues because I > do not entirely understand where the locking was happening in your > patch. > Can you try testing this with your already KTR instrumented test and > possibly report? The patch works well as far as I can tell. Thank you! There is one warning with full witness enables but it appears to be harmless (so far): Acquiring duplicate lock of same type: "sched lock" 1st sched lock 1 @ /usr/src/sys/kern/subr_turnstile.c:212 2nd sched lock 0 @ /usr/src/sys/kern/sched_ule.c:1244 KDB: stack backtrace: db_trace_self_wrapper() at 0xffffffff802d238a = db_trace_self_wrapper+0x2a kdb_backtrace() at 0xffffffff80555f4a = kdb_backtrace+0x3a _witness_debugger() at 0xffffffff8056e2bc = _witness_debugger+0x2c witness_checkorder() at 0xffffffff8056f759 = witness_checkorder+0x579 _mtx_lock_spin_flags() at 0xffffffff80504bcd = _mtx_lock_spin_flags+0x10d sched_pickcpu() at 0xffffffff80547829 = sched_pickcpu+0x199 sched_add() at 0xffffffff80547bdb = sched_add+0x14b sched_thread_priority() at 0xffffffff80548059 = sched_thread_priority+0x1c9 sched_lend_prio() at 0xffffffff80548344 = sched_lend_prio+0x14 propagate_priority() at 0xffffffff8056801e = propagate_priority+0x1ce turnstile_wait() at 0xffffffff8056959f = turnstile_wait+0x4ef _mtx_lock_sleep() at 0xffffffff805045f6 = _mtx_lock_sleep+0x486 _mtx_lock_flags() at 0xffffffff80504814 = _mtx_lock_flags+0x104 lock_mtx() at 0xffffffff805049ca = lock_mtx+0x1a _sleep() at 0xffffffff80524589 = _sleep+0x4f9 taskqueue_thread_loop() at 0xffffffff805664c8 = taskqueue_thread_loop+0xa8 fork_exit() at 0xffffffff804e5d6a = fork_exit+0x1aa fork_trampoline() at 0xffffffff806ea2ce = fork_trampoline+0xe -- Andriy Gapon
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