Date: Mon, 11 Dec 2017 20:30:58 +0000 (UTC) From: Alan Somers <asomers@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-11@freebsd.org Subject: svn commit: r326779 - stable/11/sys/cam/scsi Message-ID: <201712112030.vBBKUwP3035572@repo.freebsd.org>
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Author: asomers Date: Mon Dec 11 20:30:58 2017 New Revision: 326779 URL: https://svnweb.freebsd.org/changeset/base/326779 Log: MFC r326036: da(4): Short-circuit unnecessary BIO_FLUSH commands sys/cam/scsi/scsi_da.c Complete BIO_FLUSH commands immediately if the da(4) device hasn't been written to since the last flush. If we haven't written to the device, there is no reason to send a flush. Submitted by: gibbs Reviewed by: imp Sponsored by: Spectra Logic Corp Differential Revision: https://reviews.freebsd.org/D13106 Modified: stable/11/sys/cam/scsi/scsi_da.c Directory Properties: stable/11/ (props changed) Modified: stable/11/sys/cam/scsi/scsi_da.c ============================================================================== --- stable/11/sys/cam/scsi/scsi_da.c Mon Dec 11 20:24:29 2017 (r326778) +++ stable/11/sys/cam/scsi/scsi_da.c Mon Dec 11 20:30:58 2017 (r326779) @@ -2994,6 +2994,18 @@ more: } case BIO_FLUSH: /* + * If we don't support sync cache, or the disk + * isn't dirty, FLUSH is a no-op. Use the + * allocated * CCB for the next bio if one is + * available. + */ + if ((softc->quirks & DA_Q_NO_SYNC_CACHE) != 0 || + (softc->flags & DA_FLAG_DIRTY) == 0) { + biodone(bp); + goto skipstate; + } + + /* * BIO_FLUSH doesn't currently communicate * range data, so we synchronize the cache * over the whole disk. We also force @@ -3008,6 +3020,15 @@ more: /*lb_count*/0, SSD_FULL_SIZE, da_default_timeout*1000); + /* + * Clear the dirty flag before sending the command. + * Either this sync cache will be successful, or it + * will fail after a retry. If it fails, it is + * unlikely to be successful if retried later, so + * we'll save ourselves time by just marking the + * device clean. + */ + softc->flags &= ~DA_FLAG_DIRTY; break; case BIO_ZONE: { int error, queue_ccb;
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