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d25f89c9e9
Derived from kvm-tool patch http://thread.gmane.org/gmane.comp.emulators.kvm.devel/74309 Ingo Molnar pointed out that sending the timer signal to the whole process, just blocking it everywhere, is suboptimal with an increasing number of threads. QEMU is also using this pattern so far. Linux provides a (non-portable) way to restrict the signal to a single thread: We can use SIGEV_THREAD_ID unless we are forced to emulate signalfd via an additional thread. That case could theoretically be optimized as well, but it doesn't look worth bothering. Reviewed-by: Richard Henderson <rth@twiddle.net> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
45 lines
1.5 KiB
C
45 lines
1.5 KiB
C
/*
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* signalfd/eventfd compatibility
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*
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* Copyright IBM, Corp. 2008
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*
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* Authors:
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* Anthony Liguori <aliguori@us.ibm.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2. See
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* the COPYING file in the top-level directory.
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*
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*/
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#ifndef QEMU_COMPATFD_H
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#define QEMU_COMPATFD_H
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#include <signal.h>
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struct qemu_signalfd_siginfo {
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uint32_t ssi_signo; /* Signal number */
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int32_t ssi_errno; /* Error number (unused) */
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int32_t ssi_code; /* Signal code */
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uint32_t ssi_pid; /* PID of sender */
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uint32_t ssi_uid; /* Real UID of sender */
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int32_t ssi_fd; /* File descriptor (SIGIO) */
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uint32_t ssi_tid; /* Kernel timer ID (POSIX timers) */
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uint32_t ssi_band; /* Band event (SIGIO) */
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uint32_t ssi_overrun; /* POSIX timer overrun count */
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uint32_t ssi_trapno; /* Trap number that caused signal */
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int32_t ssi_status; /* Exit status or signal (SIGCHLD) */
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int32_t ssi_int; /* Integer sent by sigqueue(2) */
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uint64_t ssi_ptr; /* Pointer sent by sigqueue(2) */
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uint64_t ssi_utime; /* User CPU time consumed (SIGCHLD) */
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uint64_t ssi_stime; /* System CPU time consumed (SIGCHLD) */
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uint64_t ssi_addr; /* Address that generated signal
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(for hardware-generated signals) */
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uint8_t pad[48]; /* Pad size to 128 bytes (allow for
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additional fields in the future) */
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};
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int qemu_signalfd(const sigset_t *mask);
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bool qemu_signalfd_available(void);
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#endif
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