Date: Mon, 20 Nov 2017 22:27:34 +0000 (UTC) From: Alan Somers <asomers@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r326036 - head/sys/cam/scsi Message-ID: <201711202227.vAKMRYvW001932@repo.freebsd.org>
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Author: asomers Date: Mon Nov 20 22:27:33 2017 New Revision: 326036 URL: https://svnweb.freebsd.org/changeset/base/326036 Log: 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 MFC after: 3 weeks Sponsored by: Spectra Logic Corp Differential Revision: https://reviews.freebsd.org/D13106 Modified: head/sys/cam/scsi/scsi_da.c Modified: head/sys/cam/scsi/scsi_da.c ============================================================================== --- head/sys/cam/scsi/scsi_da.c Mon Nov 20 22:18:24 2017 (r326035) +++ head/sys/cam/scsi/scsi_da.c Mon Nov 20 22:27:33 2017 (r326036) @@ -3038,6 +3038,18 @@ 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 @@ -3052,6 +3064,15 @@ 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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