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ioat: reduce completion writebacks

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Do not set the completion_update bit except on
the last descriptor built before the dmacount doorbell
is written.  This allows much better batching of
completions (to match batching of the submissions).

Signed-off-by: Jim Harris <james.r.harris@intel.com>
Change-Id: Idd0281fb2e9e1ad2eb0f65f097c54fc051dfd935

Reviewed-on: https://review.gerrithub.io/c/444974
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Darek Stojaczyk <dariusz.stojaczyk@intel.com>
Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Reviewed-by: Changpeng Liu <changpeng.liu@intel.com>
This commit is contained in:
Jim Harris 2019-02-15 16:38:23 -07:00 committed by Darek Stojaczyk
parent c258d73feb
commit b01a393382
1 changed files with 5 additions and 3 deletions
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8
lib/ioat/ioat.c
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@ -161,6 +161,11 @@ ioat_submit_single(struct spdk_ioat_chan *ioat)
void
spdk_ioat_flush(struct spdk_ioat_chan *ioat)
{
uint32_t index = ioat_get_ring_index(ioat, ioat->head - 1);
union spdk_ioat_hw_desc *hw_desc;
hw_desc = &ioat->hw_ring[index];
hw_desc->dma.u.control.completion_update = 1;
ioat->regs->dmacount = (uint16_t)ioat->head;
}
@ -179,7 +184,6 @@ ioat_prep_null(struct spdk_ioat_chan *ioat)
hw_desc->dma.u.control_raw = 0;
hw_desc->dma.u.control.op = SPDK_IOAT_OP_COPY;
hw_desc->dma.u.control.null = 1;
hw_desc->dma.u.control.completion_update = 1;
hw_desc->dma.size = 8;
hw_desc->dma.src_addr = 0;
@ -210,7 +214,6 @@ ioat_prep_copy(struct spdk_ioat_chan *ioat, uint64_t dst,
hw_desc->dma.u.control_raw = 0;
hw_desc->dma.u.control.op = SPDK_IOAT_OP_COPY;
hw_desc->dma.u.control.completion_update = 1;
hw_desc->dma.size = len;
hw_desc->dma.src_addr = src;
@ -241,7 +244,6 @@ ioat_prep_fill(struct spdk_ioat_chan *ioat, uint64_t dst,
hw_desc->fill.u.control_raw = 0;
hw_desc->fill.u.control.op = SPDK_IOAT_OP_FILL;
hw_desc->fill.u.control.completion_update = 1;
hw_desc->fill.size = len;
hw_desc->fill.src_data = fill_pattern;