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From: Paolo Bonzini <pbonzini@redhat.com>
To: Peter Maydell <peter.maydell@linaro.org>,
	Michael Tokarev <mjt@tls.msk.ru>
Cc: QEMU Trivial <qemu-trivial@nongnu.org>,
	QEMU Developers <qemu-devel@nongnu.org>
Subject: Re: [Qemu-trivial] [Qemu-devel] [PULL 14/46] cpu-exec: drop dead assignment
Date: Tue, 10 Feb 2015 10:19:56 +0100	[thread overview]
Message-ID: <54D9CD3C.5050307@redhat.com> (raw)
In-Reply-To: <CAFEAcA-wWs1sTvVwOTi6Q0rXAXOOO5kWMAaZ0se5asu97B4S5Q@mail.gmail.com>



On 10/02/2015 10:15, Peter Maydell wrote:
> > -                        tb = (TranslationBlock *)(next_tb & ~TB_EXIT_MASK);
> >                          next_tb = 0;
> >                          break;
> >                      case TB_EXIT_ICOUNT_EXPIRED:
>
> True, I guess, but presumably this means we're doing unnecessary
> work in the next time round the loop re-finding the tb which we
> already had...

This is the TB_EXIT_REQUESTED case though: once the iothread runs who
knows what happens.  You might get an interrupt or a system reset that
diverts execution away from tb.

Paolo


WARNING: multiple messages have this Message-ID (diff)
From: Paolo Bonzini <pbonzini@redhat.com>
To: Peter Maydell <peter.maydell@linaro.org>,
	Michael Tokarev <mjt@tls.msk.ru>
Cc: QEMU Trivial <qemu-trivial@nongnu.org>,
	QEMU Developers <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] [PULL 14/46] cpu-exec: drop dead assignment
Date: Tue, 10 Feb 2015 10:19:56 +0100	[thread overview]
Message-ID: <54D9CD3C.5050307@redhat.com> (raw)
In-Reply-To: <CAFEAcA-wWs1sTvVwOTi6Q0rXAXOOO5kWMAaZ0se5asu97B4S5Q@mail.gmail.com>



On 10/02/2015 10:15, Peter Maydell wrote:
> > -                        tb = (TranslationBlock *)(next_tb & ~TB_EXIT_MASK);
> >                          next_tb = 0;
> >                          break;
> >                      case TB_EXIT_ICOUNT_EXPIRED:
>
> True, I guess, but presumably this means we're doing unnecessary
> work in the next time round the loop re-finding the tb which we
> already had...

This is the TB_EXIT_REQUESTED case though: once the iothread runs who
knows what happens.  You might get an interrupt or a system reset that
diverts execution away from tb.

Paolo

  reply	other threads:[~2015-02-10  9:20 UTC|newest]

Thread overview: 104+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-02-10  6:33 [Qemu-trivial] [PULL 00/46] Trivial patches for 2015-02-10 Michael Tokarev
2015-02-10  6:33 ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:33 ` [Qemu-trivial] [PULL 01/46] target-mips: Clean up switch fall through after commit fecd264 Michael Tokarev
2015-02-10  6:33   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:33 ` [Qemu-trivial] [PULL 02/46] fw_cfg: fix typos in comments: patch -> path Michael Tokarev
2015-02-10  6:33   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:33 ` [Qemu-trivial] [PULL 03/46] Add tracing to xenfb Michael Tokarev
2015-02-10  6:33   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:33 ` [Qemu-trivial] [PULL 04/46] Add trace to ps2.c Michael Tokarev
2015-02-10  6:33   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:33 ` [Qemu-trivial] [PULL 05/46] Add/convert trace calls in pcnet-pci.c Michael Tokarev
2015-02-10  6:33   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:33 ` [Qemu-trivial] [PULL 06/46] Convert some debugging printfs to trace calls in pcnet.c Michael Tokarev
2015-02-10  6:33   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:33 ` [Qemu-trivial] [PULL 07/46] vl: Fix bogus error message for implied mon ID clashing Michael Tokarev
2015-02-10  6:33   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:33 ` [Qemu-trivial] [PULL 08/46] virtfs-proxy-helper: Fix possible socket leak Michael Tokarev
2015-02-10  6:33   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:33 ` [Qemu-trivial] [PULL 09/46] linux-user/syscall.c: lock_iovec: unlock vec[i] in failure processing code block Michael Tokarev
2015-02-10  6:33   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:33 ` [Qemu-trivial] [PULL 10/46] linux-user/syscall.c: Fix typo issue for using target_vec[i].iov_len instead of target_vec[i].iov_base Michael Tokarev
2015-02-10  6:33   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:34 ` [Qemu-trivial] [PULL 11/46] linux-user/main.c: Use TARGET_SIG* instead of SIG* Michael Tokarev
2015-02-10  6:34   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:34 ` [Qemu-trivial] [PULL 12/46] linux-user/syscall.c: do_ioctl_dm: Need to call unlock_user() before going to failure return in default case Michael Tokarev
2015-02-10  6:34   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:34 ` [Qemu-trivial] [PULL 13/46] qemu-log: Correct help text of 'log cpu_reset' Michael Tokarev
2015-02-10  6:34   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:34 ` [Qemu-trivial] [PULL 14/46] cpu-exec: drop dead assignment Michael Tokarev
2015-02-10  6:34   ` [Qemu-devel] " Michael Tokarev
2015-02-10  9:15   ` [Qemu-trivial] " Peter Maydell
2015-02-10  9:15     ` Peter Maydell
2015-02-10  9:19     ` Paolo Bonzini [this message]
2015-02-10  9:19       ` Paolo Bonzini
2015-02-10  6:34 ` [Qemu-trivial] [PULL 15/46] cpu-exec: simplify icount code Michael Tokarev
2015-02-10  6:34   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:34 ` [Qemu-trivial] [PULL 16/46] qemu-sockets: improve error reporting in unix_listen_opts Michael Tokarev
2015-02-10  6:34   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:34 ` [Qemu-trivial] [PULL 17/46] aes: remove a dead return statement Michael Tokarev
2015-02-10  6:34   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:34 ` [Qemu-trivial] [PULL 18/46] vl.c: fix memory leak spotted by valgrind Michael Tokarev
2015-02-10  6:34   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:34 ` [Qemu-trivial] [PULL 19/46] qemu-sockets: Fix buffer overflow in inet_parse() Michael Tokarev
2015-02-10  6:34   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:34 ` [Qemu-trivial] [PULL 20/46] linux-user: wrong TARGET_SI_PAD_SIZE value for some targets Michael Tokarev
2015-02-10  6:34   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:34 ` [Qemu-trivial] [PULL 21/46] libcacard: stop linking against every single 3rd party library Michael Tokarev
2015-02-10  6:34   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:34 ` [Qemu-trivial] [PULL 22/46] qemu-option: Replace pointless use of g_malloc0() by g_malloc() Michael Tokarev
2015-02-10  6:34   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:34 ` [Qemu-trivial] [PULL 23/46] qemu-option: Pair g_malloc() with g_free(), not free() Michael Tokarev
2015-02-10  6:34   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:34 ` [Qemu-trivial] [PULL 24/46] spapr_vio: " Michael Tokarev
2015-02-10  6:34   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:34 ` [Qemu-trivial] [PULL 25/46] usb: " Michael Tokarev
2015-02-10  6:34   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:34 ` [Qemu-trivial] [PULL 26/46] util/uri: uri_new() can't fail, drop dead error handling Michael Tokarev
2015-02-10  6:34   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:34 ` [Qemu-trivial] [PULL 27/46] util/uri: realloc2n() " Michael Tokarev
2015-02-10  6:34   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:34 ` [Qemu-trivial] [PULL 28/46] util/uri: URI member path can be null, compare more carfully Michael Tokarev
2015-02-10  6:34   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:34 ` [Qemu-trivial] [PULL 29/46] QJSON: fix typo in author's email address Michael Tokarev
2015-02-10  6:34   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:34 ` [Qemu-trivial] [PULL 30/46] Fix name error in migration stream analyzation script Michael Tokarev
2015-02-10  6:34   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:34 ` [Qemu-trivial] [PULL 31/46] onenand: g_malloc() can't fail, bury dead error handling Michael Tokarev
2015-02-10  6:34   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:34 ` [Qemu-trivial] [PULL 32/46] rtl8139: " Michael Tokarev
2015-02-10  6:34   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:34 ` [Qemu-trivial] [PULL 33/46] kvm: " Michael Tokarev
2015-02-10  6:34   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:34 ` [Qemu-trivial] [PULL 34/46] rdma: g_malloc0() " Michael Tokarev
2015-02-10  6:34   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:34 ` [Qemu-trivial] [PULL 35/46] vnc: g_realloc() " Michael Tokarev
2015-02-10  6:34   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:34 ` [Qemu-trivial] [PULL 36/46] translate-all: Use g_try_malloc() for dynamic translator buffer Michael Tokarev
2015-02-10  6:34   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:34 ` [Qemu-trivial] [PULL 37/46] disas/cris: Fix warning caused by missing 'static' attribute Michael Tokarev
2015-02-10  6:34   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:34 ` [Qemu-trivial] [PULL 38/46] disas/sh4: " Michael Tokarev
2015-02-10  6:34   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:34 ` [Qemu-trivial] [PULL 39/46] migration: Fix warning caused by missing declaration of vmstate_dummy Michael Tokarev
2015-02-10  6:34   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:34 ` [Qemu-trivial] [PULL 40/46] migration: Fix warnings caused by missing 'static' attribute Michael Tokarev
2015-02-10  6:34   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:34 ` [Qemu-trivial] [PULL 41/46] moxie: Fix warning caused by missing include statement Michael Tokarev
2015-02-10  6:34   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:34 ` [Qemu-trivial] [PULL 42/46] serial: Fix warnings caused by missing 'static' attribute Michael Tokarev
2015-02-10  6:34   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:34 ` [Qemu-trivial] [PULL 43/46] spice: Add " Michael Tokarev
2015-02-10  6:34   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:34 ` [Qemu-trivial] [PULL 44/46] stubs: Fix warning caused by missing include statement Michael Tokarev
2015-02-10  6:34   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:34 ` [Qemu-trivial] [PULL 45/46] vga: Fix warning caused by missing 'static' attribute Michael Tokarev
2015-02-10  6:34   ` [Qemu-devel] " Michael Tokarev
2015-02-10  6:34 ` [Qemu-trivial] [PULL 46/46] virtio: " Michael Tokarev
2015-02-10  6:34   ` [Qemu-devel] " Michael Tokarev
2015-02-10  7:14 ` [Qemu-trivial] [Qemu-devel] [PULL 00/46] Trivial patches for 2015-02-10 Peter Maydell
2015-02-10  7:14   ` Peter Maydell
2015-02-10  7:29   ` [Qemu-trivial] " Michael Tokarev
2015-02-10  7:29     ` Michael Tokarev
2015-02-10 10:42     ` [Qemu-trivial] " Peter Maydell
2015-02-10 10:42       ` Peter Maydell

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