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9fea80ddf0
Introduce a configurable poll-weight parameter for adaptive polling in IOThread. This parameter replaces the hardcoded POLL_WEIGHT_SHIFT constant, allowing runtime control over how much the most recent event interval affects the next polling duration calculation. The poll-weight parameter uses a shift value where larger values decrease the weight of the current interval, enabling more gradual adjustments. When set to 0, a default value of 3 is used (meaning the current interval contributes approximately 1/8 to the weighted average). This patch also removes the hardcoded default value checks from adjust_polling_time(). Instead, poll-grow, poll-shrink, and poll-weight now use default values initialized in iothread.c during IOThread creation. Signed-off-by: Jaehoon Kim <jhkim@linux.ibm.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Acked-by: Markus Armbruster <armbru@redhat.com> Message-ID: <20260423195918.661299-4-jhkim@linux.ibm.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
86 lines
2.3 KiB
C
86 lines
2.3 KiB
C
/*
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* Event loop thread
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*
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* Copyright Red Hat Inc., 2013
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*
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* Authors:
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* Stefan Hajnoczi <stefanha@redhat.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or later.
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* See the COPYING file in the top-level directory.
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*
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*/
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#ifndef IOTHREAD_H
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#define IOTHREAD_H
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#include "qemu/aio.h"
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#include "qemu/thread.h"
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#include "qom/object.h"
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#include "system/event-loop-base.h"
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#define TYPE_IOTHREAD "iothread"
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#ifdef CONFIG_POSIX
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/*
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* Benchmark results from 2016 on NVMe SSD drives show max polling times around
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* 16-32 microseconds yield IOPS improvements for both iodepth=1 and iodepth=32
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* workloads.
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*/
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#define IOTHREAD_POLL_MAX_NS_DEFAULT 32768ULL
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#define IOTHREAD_POLL_GROW_DEFAULT 2ULL
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#define IOTHREAD_POLL_SHRINK_DEFAULT 2ULL
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#define IOTHREAD_POLL_WEIGHT_DEFAULT 3ULL
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#else
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#define IOTHREAD_POLL_MAX_NS_DEFAULT 0ULL
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#define IOTHREAD_POLL_GROW_DEFAULT 0ULL
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#define IOTHREAD_POLL_SHRINK_DEFAULT 0ULL
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#define IOTHREAD_POLL_WEIGHT_DEFAULT 0ULL
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#endif
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struct IOThread {
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EventLoopBase parent_obj;
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QemuThread thread;
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AioContext *ctx;
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bool run_gcontext; /* whether we should run gcontext */
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GMainContext *worker_context;
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GMainLoop *main_loop;
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QemuSemaphore init_done_sem; /* is thread init done? */
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bool stopping; /* has iothread_stop() been called? */
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bool running; /* should iothread_run() continue? */
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int thread_id;
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/* AioContext poll parameters */
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int64_t poll_max_ns;
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int64_t poll_grow;
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int64_t poll_shrink;
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int64_t poll_weight;
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};
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typedef struct IOThread IOThread;
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DECLARE_INSTANCE_CHECKER(IOThread, IOTHREAD,
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TYPE_IOTHREAD)
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char *iothread_get_id(IOThread *iothread);
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IOThread *iothread_by_id(const char *id);
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AioContext *iothread_get_aio_context(IOThread *iothread);
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GMainContext *iothread_get_g_main_context(IOThread *iothread);
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/*
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* Helpers used to allocate iothreads for internal use. These
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* iothreads will not be seen by monitor clients when query using
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* "query-iothreads".
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*/
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IOThread *iothread_create(const char *id, Error **errp);
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void iothread_stop(IOThread *iothread);
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void iothread_destroy(IOThread *iothread);
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/*
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* Returns true if executing within IOThread context,
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* false otherwise.
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*/
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bool qemu_in_iothread(void);
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#endif /* IOTHREAD_H */
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