cam iosched: Schedule cam_iosched_ticker() quanta times per second
Previously callout_reset() was called with a "ticks" value that was off by one. As a result cam_iosched_ticker() was called a bit too frequently: On systems with hz=1000 a quanta value of 200 resulted in ~250 calls and a value of 100 in ~111 calls. For the "queue_depth" and "bandwidth" limiters the difference doesn't matter but the "iops" limiter depends on the scheduling to enforce the correct maximum. PR: 221956 Obtained from: ElectroBSD Submitted by: Fabian Keil Differential Revision: https://reviews.freebsd.org/D12350
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svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=323831
@ -533,7 +533,7 @@ cam_iosched_ticker(void *arg)
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sbintime_t now, delta;
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int pending;
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callout_reset(&isc->ticker, hz / isc->quanta - 1, cam_iosched_ticker, isc);
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callout_reset(&isc->ticker, hz / isc->quanta, cam_iosched_ticker, isc);
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now = sbinuptime();
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delta = now - isc->last_time;
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@ -798,7 +798,7 @@ cam_iosched_limiter_sysctl(SYSCTL_HANDLER_ARGS)
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return error;
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}
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/* Note: disk load averate requires ticker to be always running */
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callout_reset(&isc->ticker, hz / isc->quanta - 1, cam_iosched_ticker, isc);
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callout_reset(&isc->ticker, hz / isc->quanta, cam_iosched_ticker, isc);
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isc->flags |= CAM_IOSCHED_FLAG_CALLOUT_ACTIVE;
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cam_periph_unlock(isc->periph);
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@ -1055,7 +1055,7 @@ cam_iosched_init(struct cam_iosched_softc **iscp, struct cam_periph *periph)
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callout_init_mtx(&(*iscp)->ticker, cam_periph_mtx(periph), 0);
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(*iscp)->periph = periph;
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cam_iosched_cl_init(&(*iscp)->cl, *iscp);
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callout_reset(&(*iscp)->ticker, hz / (*iscp)->quanta - 1, cam_iosched_ticker, *iscp);
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callout_reset(&(*iscp)->ticker, hz / (*iscp)->quanta, cam_iosched_ticker, *iscp);
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(*iscp)->flags |= CAM_IOSCHED_FLAG_CALLOUT_ACTIVE;
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}
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#endif
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