Re: [PATCH 09/15] swiotlb: make the swiotlb_init interface more useful
From: Christoph Hellwig <hch@lst.de>
Date: 2022-06-01 18:22:52
Also in:
linux-arm-kernel, linux-hyperv, linux-iommu, linux-mips, linux-pci, linux-riscv, linux-s390, xen-devel
Subsystem:
dma mapping helpers, the rest · Maintainers:
Marek Szyprowski, Linus Torvalds
On Wed, Jun 01, 2022 at 11:11:57AM -0700, Nathan Chancellor wrote:
On Wed, Jun 01, 2022 at 07:57:43PM +0200, Christoph Hellwig wrote:quoted
On Wed, Jun 01, 2022 at 10:46:54AM -0700, Nathan Chancellor wrote:quoted
On Wed, Jun 01, 2022 at 07:34:41PM +0200, Christoph Hellwig wrote:quoted
Can you send me the full dmesg and the content of /sys/kernel/debug/swiotlb/io_tlb_nslabs for a good and a bad boot?Sure thing, they are attached! If there is anything else I can provide or test, I am more than happy to do so.Nothing interesting. But the performance numbers almost look like swiotlb=force got ignored before (even if I can't explain why).I was able to get my performance back with this diff but I don't know if this is a hack or a proper fix in the context of the series.
This looks good, but needs a little tweak. I'd go for this variant of it:
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index dfa1de89dc944..cb50f8d383606 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c@@ -192,7 +192,7 @@ void __init swiotlb_update_mem_attributes(void) } static void swiotlb_init_io_tlb_mem(struct io_tlb_mem *mem, phys_addr_t start, - unsigned long nslabs, bool late_alloc) + unsigned long nslabs, unsigned int flags, bool late_alloc) { void *vaddr = phys_to_virt(start); unsigned long bytes = nslabs << IO_TLB_SHIFT, i;
@@ -203,8 +203,7 @@ static void swiotlb_init_io_tlb_mem(struct io_tlb_mem *mem, phys_addr_t start, mem->index = 0; mem->late_alloc = late_alloc; - if (swiotlb_force_bounce) - mem->force_bounce = true; + mem->force_bounce = swiotlb_force_bounce || (flags & SWIOTLB_FORCE); spin_lock_init(&mem->lock); for (i = 0; i < mem->nslabs; i++) {
@@ -275,8 +274,7 @@ void __init swiotlb_init_remap(bool addressing_limit, unsigned int flags, panic("%s: Failed to allocate %zu bytes align=0x%lx\n", __func__, alloc_size, PAGE_SIZE); - swiotlb_init_io_tlb_mem(mem, __pa(tlb), nslabs, false); - mem->force_bounce = flags & SWIOTLB_FORCE; + swiotlb_init_io_tlb_mem(mem, __pa(tlb), nslabs, flags, false); if (flags & SWIOTLB_VERBOSE) swiotlb_print_info();
@@ -348,7 +346,7 @@ int swiotlb_init_late(size_t size, gfp_t gfp_mask, set_memory_decrypted((unsigned long)vstart, (nslabs << IO_TLB_SHIFT) >> PAGE_SHIFT); - swiotlb_init_io_tlb_mem(mem, virt_to_phys(vstart), nslabs, true); + swiotlb_init_io_tlb_mem(mem, virt_to_phys(vstart), nslabs, 0, true); swiotlb_print_info(); return 0;
@@ -835,8 +833,8 @@ static int rmem_swiotlb_device_init(struct reserved_mem *rmem, set_memory_decrypted((unsigned long)phys_to_virt(rmem->base), rmem->size >> PAGE_SHIFT); - swiotlb_init_io_tlb_mem(mem, rmem->base, nslabs, false); - mem->force_bounce = true; + swiotlb_init_io_tlb_mem(mem, rmem->base, nslabs, SWIOTLB_FORCE, + false); mem->for_alloc = true; rmem->priv = mem;