Once again throw out the calculation of si_iosize_max and set it to 64K.
Although it can go higher, it is not safe to so do on arrays with many members. Compromise by adding a tunable, "hw.aac.iosize_max" that can be set at boottime. Also document in the aac(4) manpage. MFC after: 4 weeks
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svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=81154
@ -100,6 +100,18 @@ disk/container interface
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.It Pa /boot/kernel/aac.ko
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aac loadable module
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.El
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.Sh TUNING
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The read-only sysctl
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.Va hw.aac.iosize_max
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defautls to 65536 and may be set at boot time to another value via
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.Xr loader 8 .
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This value determines the maximum data transfer size allowed
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to/from an array. Setting it higher will result in better performance,
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especially for large sequential access patterns. BEWARE: internal limitations
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of the card limit this value to 64K for arrays with many members. While it
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may be safe to raise this value, do so AT YOUR OWN RISK. Note also that
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performance peaks at a value of 96K, and drops off dramatically at 128K, due
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to other limitations of the card.
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.Sh DIAGNOSTICS
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Compiling with
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.Dv AAC_DEBUG
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@ -40,6 +40,7 @@
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#include <sys/systm.h>
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#include <sys/malloc.h>
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#include <sys/kernel.h>
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#include <sys/sysctl.h>
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#include <dev/aac/aac_compat.h>
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@ -183,6 +184,9 @@ static struct cdevsw aac_cdevsw = {
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0, /* flags */
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};
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/* sysctl node */
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SYSCTL_NODE(_hw, OID_AUTO, aac, CTLFLAG_RD, 0, "AAC driver parameters");
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/******************************************************************************
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******************************************************************************
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Device Interface
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@ -34,6 +34,7 @@
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/sysctl.h>
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#include <dev/aac/aac_compat.h>
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#include <sys/bus.h>
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@ -101,6 +102,14 @@ static driver_t aac_disk_driver = {
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DRIVER_MODULE(aacd, aac, aac_disk_driver, aac_disk_devclass, 0, 0);
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/* sysctl tunables */
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static unsigned int aac_iosize_max = 65536; /* due to limits of the card */
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TUNABLE_INT("hw.aac.iosize_max", &aac_iosize_max);
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SYSCTL_DECL(_hw_aac);
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SYSCTL_UINT(_hw_aac, OID_AUTO, iosize_max, CTLFLAG_RD, &aac_iosize_max, 0,
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"Max I/O size per transfer to an array");
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/******************************************************************************
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* Handle open from generic layer.
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*
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@ -215,8 +224,6 @@ static int
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aac_disk_attach(device_t dev)
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{
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struct aac_disk *sc = (struct aac_disk *)device_get_softc(dev);
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int sgspace;
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int maxsg;
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debug_called(4);
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@ -259,21 +266,7 @@ aac_disk_attach(device_t dev)
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disks_registered++;
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#endif
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/*
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* We can calculate the maximum number of s/g entries based on the size of
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* the FIB and the command structures packed within it.
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*/
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sgspace = (sizeof(struct aac_fib) - sizeof(struct aac_fib_header) -
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imax(sizeof(struct aac_blockwrite),
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sizeof(struct aac_blockread)));
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maxsg = (sgspace - sizeof(struct aac_sg_table)) /
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sizeof(struct aac_sg_entry);
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/*
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* set the maximum I/O size to the theoretical worst maximum allowed by the
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* S/G list size
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*/
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sc->ad_dev_t->si_iosize_max = (maxsg - 1) * PAGE_SIZE;
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sc->ad_dev_t->si_iosize_max = aac_iosize_max;
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return (0);
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}
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