Limit stripesize reported from nvd(4) to 4K
Intel NVMe controllers have a slow path for I/Os that span a 128KB stripe boundary but ZFS limits ashift, which is derived from d_stripesize, to 13 (8KB) so we limit the stripesize reported to geom(8) to 4KB. This may result in a small number of additional I/Os to require splitting in nvme(4), however the NVMe I/O path is very efficient so these additional I/Os will cause very minimal (if any) difference in performance or CPU utilisation. This can be controller by the new sysctl kern.nvme.max_optimal_sectorsize. MFC after: 1 week Sponsored by: Multiplay Differential Revision: https://reviews.freebsd.org/D4446
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svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=292074
@ -279,7 +279,7 @@ nvd_new_disk(struct nvme_namespace *ns, void *ctrlr_arg)
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disk->d_sectorsize = nvme_ns_get_sector_size(ns);
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disk->d_mediasize = (off_t)nvme_ns_get_size(ns);
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disk->d_delmaxsize = (off_t)nvme_ns_get_size(ns);
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disk->d_stripesize = nvme_ns_get_stripesize(ns);
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disk->d_stripesize = nvme_ns_get_optimal_sector_size(ns);
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if (TAILQ_EMPTY(&disk_head))
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disk->d_unit = 0;
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@ -870,6 +870,7 @@ const char * nvme_ns_get_serial_number(struct nvme_namespace *ns);
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const char * nvme_ns_get_model_number(struct nvme_namespace *ns);
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const struct nvme_namespace_data *
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nvme_ns_get_data(struct nvme_namespace *ns);
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uint32_t nvme_ns_get_optimal_sector_size(struct nvme_namespace *ns);
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uint32_t nvme_ns_get_stripesize(struct nvme_namespace *ns);
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int nvme_ns_bio_process(struct nvme_namespace *ns, struct bio *bp,
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@ -45,6 +45,8 @@ __FBSDID("$FreeBSD$");
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#include "nvme_private.h"
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extern int nvme_max_optimal_sectorsize;
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static void nvme_bio_child_inbed(struct bio *parent, int bio_error);
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static void nvme_bio_child_done(void *arg,
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const struct nvme_completion *cpl);
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@ -217,6 +219,22 @@ nvme_ns_get_stripesize(struct nvme_namespace *ns)
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return (ns->stripesize);
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}
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uint32_t
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nvme_ns_get_optimal_sector_size(struct nvme_namespace *ns)
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{
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uint32_t stripesize;
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stripesize = nvme_ns_get_stripesize(ns);
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if (stripesize == 0)
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return nvme_ns_get_sector_size(ns);
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if (nvme_max_optimal_sectorsize == 0)
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return (stripesize);
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return (MIN(stripesize, nvme_max_optimal_sectorsize));
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}
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static void
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nvme_ns_bio_done(void *arg, const struct nvme_completion *status)
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{
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@ -33,6 +33,22 @@ __FBSDID("$FreeBSD$");
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#include "nvme_private.h"
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SYSCTL_NODE(_kern, OID_AUTO, nvme, CTLFLAG_RD, 0, "NVM Express");
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/*
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* Intel NVMe controllers have a slow path for I/Os that span a 128KB
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* stripe boundary but ZFS limits ashift, which is derived from
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* d_stripesize, to 13 (8KB) so we limit the stripesize reported to
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* geom(8) to 4KB by default.
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*
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* This may result in a small number of additional I/Os to require
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* splitting in nvme(4), however the NVMe I/O path is very efficient
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* so these additional I/Os will cause very minimal (if any) difference
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* in performance or CPU utilisation.
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*/
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int nvme_max_optimal_sectorsize = 1<<12;
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SYSCTL_INT(_kern_nvme, OID_AUTO, max_optimal_sectorsize, CTLFLAG_RWTUN,
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&nvme_max_optimal_sectorsize, 0, "The maximum optimal sectorsize reported");
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/*
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* CTLTYPE_S64 and sysctl_handle_64 were added in r217616. Define these
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* explicitly here for older kernels that don't include the r217616
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