From: Alexander Bluhm <bluhm@openbsd.org>
Subject: Re: ice max vectors
To: Mark Kettenis <mark.kettenis@xs4all.nl>
Cc: tech@openbsd.org
Date: Tue, 24 Feb 2026 22:35:31 +0100

On Tue, Feb 24, 2026 at 09:45:36PM +0100, Mark Kettenis wrote:
> > #define ICE_MAX_VECTORS		8 /* XXX this is pretty arbitrary */
> > Does anyone know a more realistic number for ice than 8 ?
> 
> You could look at pcidump -v output on a few machines.  MSI should
> report the number of vectors; for MSI-X the table size should be
> equivalent.

 138:0:1: Intel E810-XXV SFP
        0x0070: Capability 0x11: Extended Message Signalled Interrupts (MSI-X)
                Enabled: yes; table size 1024 (BAR 3:0)

 225:0:0: Intel E810-C QSFP
        0x0070: Capability 0x11: Extended Message Signalled Interrupts (MSI-X)
                Enabled: yes; table size 1024 (BAR 3:0)

Should I change it to 1024?  Only sc_vectors could become larger,
but it is limited by ncpus.

        sc->sc_nvectors = MIN(sc->sc_nmsix_max, ncpus);
        sc->sc_nvectors = MIN(sc->sc_nvectors, ICE_MAX_VECTORS);
        sc->sc_vectors = mallocarray(sizeof(*sc->sc_vectors), sc->sc_nvectors,
            M_DEVBUF, M_WAITOK|M_CANFAIL|M_ZERO);

bluhm

Index: dev/pci/if_ice.c
===================================================================
RCS file: /data/mirror/openbsd/cvs/src/sys/dev/pci/if_ice.c,v
diff -u -p -r1.68 if_ice.c
--- dev/pci/if_ice.c	24 Feb 2026 20:14:29 -0000	1.68
+++ dev/pci/if_ice.c	24 Feb 2026 21:29:55 -0000
@@ -263,7 +263,7 @@ struct ice_intr_vector {
 	pci_intr_handle_t	 ih;
 };
 
-#define ICE_MAX_VECTORS			8 /* XXX this is pretty arbitrary */
+#define ICE_MAX_VECTORS			1024
 
 static struct rwlock ice_sff_lock = RWLOCK_INITIALIZER("icesff");
 
@@ -308,8 +308,8 @@ struct ice_softc {
 
 	/* isc_* fields inherited from FreeBSD iflib struct if_softc_ctx */
 	int isc_tx_nsegments;
-	int isc_ntxd[8];
-	int isc_nrxd[8];
+	int isc_ntxd[MIN(ICE_MAX_VECTORS, IF_MAX_VECTORS)];
+	int isc_nrxd[MIN(ICE_MAX_VECTORS, IF_MAX_VECTORS)];
 	int isc_tx_tso_segments_max;
 	int isc_tx_tso_size_max;
 	int isc_tx_tso_segsize_max;
@@ -339,7 +339,7 @@ struct ice_softc {
 
 	int rebuild_ticks;
 
-	int sw_intr[ICE_MAX_VECTORS];
+	int sw_intr[MIN(ICE_MAX_VECTORS, IF_MAX_VECTORS) + 1];
 };
 
 static int ice_rxrinfo(struct ice_softc *, struct if_rxrinfo *);