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Make software iSCSI more configurable.

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Move software iSCSI tunables/sysctls into kern.icl.soft subtree.
Replace several hardcoded length constants there with variables.

While there, stretch the limits to better match Linux' open-iscsi
and our own initiator with new MAXPHYS of 1MB.  Our CTL target is
also optimized for up to 1MB I/Os, so there is also a match now.
For Windows 10 and VMware 6.7 initiators at default settings it
should make no change, since previous limits were sufficient there.

Tests of QD1 1MB writes from FreeBSD over 10GigE link show throughput
increase by 29% on idle connection and 132% with concurrent QD8 reads.

MFC after:	3 days
Sponsored by:	iXsystems, Inc.
This commit is contained in:
Alexander Motin 2021-01-28 15:53:49 -05:00
parent d2c9d0a418
commit b75168ed24
2 changed files with 25 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
sys/dev/iscsi/icl.h
View File

@ -89,8 +89,6 @@ struct icl_pdu {
#define ICL_CONN_STATE_DATA 4
#define ICL_CONN_STATE_DATA_DIGEST 5
#define ICL_MAX_DATA_SEGMENT_LENGTH (128 * 1024)
#define ICL_NOCOPY (1 << 30)
struct icl_conn {

45
sys/dev/iscsi/icl_soft.c
View File

@ -72,18 +72,29 @@ struct icl_soft_pdu {
int error;
};
SYSCTL_NODE(_kern_icl, OID_AUTO, soft, CTLFLAG_RD | CTLFLAG_MPSAFE, 0,
"Software iSCSI");
static int coalesce = 1;
SYSCTL_INT(_kern_icl, OID_AUTO, coalesce, CTLFLAG_RWTUN,
SYSCTL_INT(_kern_icl_soft, OID_AUTO, coalesce, CTLFLAG_RWTUN,
&coalesce, 0, "Try to coalesce PDUs before sending");
static int partial_receive_len = 128 * 1024;
SYSCTL_INT(_kern_icl, OID_AUTO, partial_receive_len, CTLFLAG_RWTUN,
static int partial_receive_len = 256 * 1024;
SYSCTL_INT(_kern_icl_soft, OID_AUTO, partial_receive_len, CTLFLAG_RWTUN,
&partial_receive_len, 0, "Minimum read size for partially received "
"data segment");
static int sendspace = 1048576;
SYSCTL_INT(_kern_icl, OID_AUTO, sendspace, CTLFLAG_RWTUN,
static int max_data_segment_length = 256 * 1024;
SYSCTL_INT(_kern_icl_soft, OID_AUTO, max_data_segment_length, CTLFLAG_RWTUN,
&max_data_segment_length, 0, "Maximum data segment length");
static int first_burst_length = 1024 * 1024;
SYSCTL_INT(_kern_icl_soft, OID_AUTO, first_burst_length, CTLFLAG_RWTUN,
&first_burst_length, 0, "First burst length");
static int max_burst_length = 1024 * 1024;
SYSCTL_INT(_kern_icl_soft, OID_AUTO, max_burst_length, CTLFLAG_RWTUN,
&max_burst_length, 0, "Maximum burst length");
static int sendspace = 1536 * 1024;
SYSCTL_INT(_kern_icl_soft, OID_AUTO, sendspace, CTLFLAG_RWTUN,
&sendspace, 0, "Default send socket buffer size");
static int recvspace = 1048576;
SYSCTL_INT(_kern_icl, OID_AUTO, recvspace, CTLFLAG_RWTUN,
static int recvspace = 1536 * 1024;
SYSCTL_INT(_kern_icl_soft, OID_AUTO, recvspace, CTLFLAG_RWTUN,
&recvspace, 0, "Default receive socket buffer size");
static MALLOC_DEFINE(M_ICL_SOFT, "icl_soft", "iSCSI software backend");
@ -663,10 +674,8 @@ icl_conn_receive_pdu(struct icl_conn *ic, size_t *availablep)
len = icl_pdu_data_segment_length(request);
if (len > ic->ic_max_data_segment_length) {
ICL_WARN("received data segment "
"length %zd is larger than negotiated "
"MaxDataSegmentLength %zd; "
"dropping connection",
len, ic->ic_max_data_segment_length);
"length %zd is larger than negotiated; "
"dropping connection", len);
error = EINVAL;
break;
}
@ -1230,7 +1239,7 @@ icl_soft_new_conn(const char *name, struct mtx *lock)
#ifdef DIAGNOSTIC
refcount_init(&ic->ic_outstanding_pdus, 0);
#endif
ic->ic_max_data_segment_length = ICL_MAX_DATA_SEGMENT_LENGTH;
ic->ic_max_data_segment_length = max_data_segment_length;
ic->ic_name = name;
ic->ic_offload = "None";
ic->ic_unmapped = false;
@ -1280,10 +1289,6 @@ icl_conn_start(struct icl_conn *ic)
* For sendspace, this is required because the current code cannot
* send a PDU in pieces; thus, the minimum buffer size is equal
* to the maximum PDU size. "+4" is to account for possible padding.
*
* What we should actually do here is to use autoscaling, but set
* some minimal buffer size to "minspace". I don't know a way to do
* that, though.
*/
minspace = sizeof(struct iscsi_bhs) + ic->ic_max_data_segment_length +
ISCSI_HEADER_DIGEST_SIZE + ISCSI_DATA_DIGEST_SIZE + 4;
@ -1520,10 +1525,10 @@ static int
icl_soft_limits(struct icl_drv_limits *idl)
{
idl->idl_max_recv_data_segment_length = 128 * 1024;
idl->idl_max_send_data_segment_length = 128 * 1024;
idl->idl_max_burst_length = 262144;
idl->idl_first_burst_length = idl->idl_max_burst_length;
idl->idl_max_recv_data_segment_length = max_data_segment_length;
idl->idl_max_send_data_segment_length = max_data_segment_length;
idl->idl_max_burst_length = max_burst_length;
idl->idl_first_burst_length = first_burst_length;
return (0);
}