From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nathan Chancellor Date: Wed, 01 Jun 2022 18:11:57 +0000 Subject: Re: [PATCH 09/15] swiotlb: make the swiotlb_init interface more useful Message-Id: List-Id: References: <20220404050559.132378-1-hch@lst.de> <20220404050559.132378-10-hch@lst.de> <20220601173441.GB27582@lst.de> <20220601175743.GA28082@lst.de> In-Reply-To: <20220601175743.GA28082@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Christoph Hellwig Cc: iommu@lists.linux-foundation.org, x86@kernel.org, Anshuman Khandual , Tom Lendacky , Konrad Rzeszutek Wilk , Stefano Stabellini , Boris Ostrovsky , Juergen Gross , Joerg Roedel , David Woodhouse , Lu Baolu , Robin Murphy , linux-arm-kernel@lists.infradead.org, xen-devel@lists.xenproject.org, linux-ia64@vger.kernel.org, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-hyperv@vger.kernel.org, tboot-devel@lists.sourceforge.net, linux-pci@vger.kernel.org On Wed, Jun 01, 2022 at 07:57:43PM +0200, Christoph Hellwig wrote: > On Wed, Jun 01, 2022 at 10:46:54AM -0700, Nathan Chancellor wrote: > > On Wed, Jun 01, 2022 at 07:34:41PM +0200, Christoph Hellwig wrote: > > > 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. diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index dfa1de89dc94..0bfb2fe3d8c5 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -276,7 +276,7 @@ void __init swiotlb_init_remap(bool addressing_limit, unsigned int flags, __func__, alloc_size, PAGE_SIZE); swiotlb_init_io_tlb_mem(mem, __pa(tlb), nslabs, false); - mem->force_bounce = flags & SWIOTLB_FORCE; + mem->force_bounce = swiotlb_force_bounce || (flags & SWIOTLB_FORCE); if (flags & SWIOTLB_VERBOSE) swiotlb_print_info(); > Do you get a similar performance with the new kernel without > swiotlb=force as the old one with that argument by any chance? I'll see if I can test that, as I am not sure I have control over those cmdline arguments. Cheers, Nathan