From: Wei Chen <Wei.Chen@arm.com>
To: Jan Beulich <jbeulich@suse.com>
Cc: Bertrand Marquis <Bertrand.Marquis@arm.com>,
"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
"sstabellini@kernel.org" <sstabellini@kernel.org>,
"julien@xen.org" <julien@xen.org>
Subject: RE: [PATCH 04/37] xen: introduce an arch helper for default dma zone status
Date: Tue, 18 Jan 2022 07:51:08 +0000 [thread overview]
Message-ID: <PAXPR08MB7420CD3B7CFB4D2D81019F479E589@PAXPR08MB7420.eurprd08.prod.outlook.com> (raw)
In-Reply-To: <345944c4-78dd-8009-6f64-f9c7901a5497@suse.com>
Hi Jan,
> -----Original Message-----
> From: Jan Beulich <jbeulich@suse.com>
> Sent: 2022年1月18日 0:11
> To: Wei Chen <Wei.Chen@arm.com>
> Cc: Bertrand Marquis <Bertrand.Marquis@arm.com>; xen-
> devel@lists.xenproject.org; sstabellini@kernel.org; julien@xen.org
> Subject: Re: [PATCH 04/37] xen: introduce an arch helper for default dma
> zone status
>
> I realize this series has been pending for a long time, but I don't
> recall any indication that it would have been dropped. Hence as a
> first try, a few comments on this relatively simple change. I'm
> sorry it to have taken so long to get to it.
>
Thanks for reviewing this series and lift it up. We are still
working on this series and will send a new version soon.
> On 23.09.2021 14:02, Wei Chen wrote:
> > In current code, when Xen is running in a multiple nodes NUMA
> > system, it will set dma_bitsize in end_boot_allocator to reserve
> > some low address memory for DMA.
> >
> > There are some x86 implications in current implementation. Becuase
> > on x86, memory starts from 0. On a multiple nodes NUMA system, if
> > a single node contains the majority or all of the DMA memory. x86
> > prefer to give out memory from non-local allocations rather than
> > exhausting the DMA memory ranges. Hence x86 use dma_bitsize to set
> > aside some largely arbitrary amount memory for DMA memory ranges.
> > The allocations from these memory ranges would happen only after
> > exhausting all other nodes' memory.
> >
> > But the implications are not shared across all architectures. For
> > example, Arm doesn't have these implications. So in this patch, we
> > introduce an arch_have_default_dmazone helper for arch to determine
> > that it need to set dma_bitsize for reserve DMA allocations or not.
>
> How would Arm guarantee availability of memory below a certain
> boundary for limited-capability devices? Or is there no need
> because there's an assumption that I/O for such devices would
> always pass through an IOMMU, lifting address size restrictions?
> (I guess in a !PV build on x86 we could also get rid of such a
> reservation.)
On Arm, we still can have some devices with limited DMA capability.
And we also don't force all such devices to use IOMMU. This devices
will affect the dma_bitsize. Like RPi platform, it sets its dma_bitsize
to 30. But in multiple NUMA nodes system, Arm doesn't have a default
DMA zone. Multiple nodes is not a constraint on dma_bitsize. And some
previous discussions are placed here [1].
>
> > --- a/xen/arch/x86/numa.c
> > +++ b/xen/arch/x86/numa.c
> > @@ -371,6 +371,11 @@ unsigned int __init arch_get_dma_bitsize(void)
> > + PAGE_SHIFT, 32);
> > }
> >
> > +unsigned int arch_have_default_dmazone(void)
> > +{
> > + return ( num_online_nodes() > 1 ) ? 1 : 0;
> > +}
>
> According to the expression and ...
>
> > --- a/xen/common/page_alloc.c
> > +++ b/xen/common/page_alloc.c
> > @@ -1889,7 +1889,7 @@ void __init end_boot_allocator(void)
> > }
> > nr_bootmem_regions = 0;
> >
> > - if ( !dma_bitsize && (num_online_nodes() > 1) )
> > + if ( !dma_bitsize && arch_have_default_dmazone() )
> > dma_bitsize = arch_get_dma_bitsize();
>
> ... the use site, you mean the function to return boolean. Please
> indicate so by making it have a return type of "bool". Independent
> of that you don't need a conditional expression above, nor
> (malformed) use of parentheses. I further wonder whether ...
>
I will fix them in next version. But I am not very clear about
this comment "of that you don't need a conditional expression above",
The "above" indicates this line:
"return ( num_online_nodes() > 1 ) ? 1 : 0;"?
> > --- a/xen/include/asm-arm/numa.h
> > +++ b/xen/include/asm-arm/numa.h
> > @@ -25,6 +25,11 @@ extern mfn_t first_valid_mfn;
> > #define node_start_pfn(nid) (mfn_x(first_valid_mfn))
> > #define __node_distance(a, b) (20)
> >
> > +static inline unsigned int arch_have_default_dmazone(void)
> > +{
> > + return 0;
> > +}
>
> ... like this one, x86'es couldn't be inline as well. If indeed
> it can't be, making it a macro may still be better (and avoid a
> further comment regarding the lack of __init).
Ok, that would be better, I will do it in next version.
>
> Jan
[1] https://lists.xenproject.org/archives/html/xen-devel/2021-08/msg00772.html
next prev parent reply other threads:[~2022-01-18 7:51 UTC|newest]
Thread overview: 192+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-23 12:01 [PATCH 00/37] Add device tree based NUMA support to Arm Wei Chen
2021-09-23 12:02 ` [PATCH 01/37] xen/arm: Print a 64-bit number in hex from early uart Wei Chen
2021-09-23 12:02 ` [PATCH 02/37] xen: introduce a Kconfig option to configure NUMA nodes number Wei Chen
2021-09-23 23:45 ` Stefano Stabellini
2021-09-24 1:24 ` Wei Chen
2021-09-24 8:55 ` Jan Beulich
2021-09-24 10:33 ` Wei Chen
2021-09-24 10:47 ` Jan Beulich
2021-09-23 12:02 ` [PATCH 03/37] xen/x86: Initialize memnodemapsize while faking NUMA node Wei Chen
2021-09-24 8:57 ` Jan Beulich
2021-09-24 10:34 ` Wei Chen
2021-09-23 12:02 ` [PATCH 04/37] xen: introduce an arch helper for default dma zone status Wei Chen
2021-09-23 23:55 ` Stefano Stabellini
2021-09-24 1:50 ` Wei Chen
2022-01-17 16:10 ` Jan Beulich
2022-01-18 7:51 ` Wei Chen [this message]
2022-01-18 8:16 ` Jan Beulich
2022-01-18 9:20 ` Wei Chen
2022-01-18 14:16 ` Jan Beulich
2022-01-19 2:49 ` Wei Chen
2022-01-19 7:50 ` Jan Beulich
2022-01-19 8:33 ` Wei Chen
2021-09-23 12:02 ` [PATCH 05/37] xen: decouple NUMA from ACPI in Kconfig Wei Chen
2021-09-23 12:02 ` [PATCH 06/37] xen/arm: use !CONFIG_NUMA to keep fake NUMA API Wei Chen
2021-09-24 0:05 ` Stefano Stabellini
2021-09-24 10:21 ` Wei Chen
2021-09-23 12:02 ` [PATCH 07/37] xen/x86: use paddr_t for addresses in NUMA node structure Wei Chen
2021-09-24 0:11 ` Stefano Stabellini
2021-09-24 0:13 ` Stefano Stabellini
2021-09-24 3:00 ` Wei Chen
2022-01-18 15:22 ` Jan Beulich
2022-01-19 6:33 ` Wei Chen
2022-01-19 7:55 ` Jan Beulich
2022-01-19 8:36 ` Wei Chen
2021-09-23 12:02 ` [PATCH 08/37] xen/x86: add detection of discontinous node memory range Wei Chen
2021-09-24 0:25 ` Stefano Stabellini
2021-09-24 4:28 ` Wei Chen
2021-09-24 19:52 ` Stefano Stabellini
2021-09-26 10:11 ` Wei Chen
2021-09-27 3:13 ` Stefano Stabellini
2021-09-27 5:05 ` Stefano Stabellini
2021-09-27 9:50 ` Wei Chen
2021-09-27 17:19 ` Stefano Stabellini
2021-09-28 4:41 ` Wei Chen
2021-09-28 4:59 ` Stefano Stabellini
2022-01-18 16:13 ` Jan Beulich
2022-01-19 7:33 ` Wei Chen
2022-01-19 8:01 ` Jan Beulich
2022-01-19 8:24 ` Wei Chen
2021-09-23 12:02 ` [PATCH 09/37] xen/x86: introduce two helpers to access memory hotplug end Wei Chen
2021-09-24 0:29 ` Stefano Stabellini
2021-09-24 4:21 ` Wei Chen
2022-01-24 16:24 ` Jan Beulich
2022-01-26 7:53 ` Wei Chen
2021-09-23 12:02 ` [PATCH 10/37] xen/x86: use helpers to access/update mem_hotplug Wei Chen
2021-09-24 0:31 ` Stefano Stabellini
2021-09-24 4:29 ` Wei Chen
2022-01-24 16:29 ` Jan Beulich
2022-01-26 7:58 ` Wei Chen
2021-09-23 12:02 ` [PATCH 11/37] xen/x86: abstract neutral code from acpi_numa_memory_affinity_init Wei Chen
2021-09-24 0:38 ` Stefano Stabellini
2022-01-24 16:50 ` Jan Beulich
2022-01-26 10:39 ` Wei Chen
2021-09-23 12:02 ` [PATCH 12/37] xen/x86: decouple nodes_cover_memory from E820 map Wei Chen
2021-09-24 0:39 ` Stefano Stabellini
2022-01-24 16:59 ` Jan Beulich
2022-01-27 8:03 ` Wei Chen
2022-01-27 8:08 ` Jan Beulich
2022-01-27 9:03 ` Wei Chen
2022-01-27 9:22 ` Jan Beulich
2022-01-27 9:27 ` Wei Chen
2021-09-23 12:02 ` [PATCH 13/37] xen/x86: decouple processor_nodes_parsed from acpi numa functions Wei Chen
2021-09-24 0:40 ` Stefano Stabellini
2022-01-25 9:49 ` Jan Beulich
2022-01-27 8:06 ` Wei Chen
2021-09-23 12:02 ` [PATCH 14/37] xen/x86: use name fw_numa to replace acpi_numa Wei Chen
2021-09-24 0:40 ` Stefano Stabellini
2022-01-25 10:12 ` Jan Beulich
2022-01-27 8:09 ` Wei Chen
2021-09-23 12:02 ` [PATCH 15/37] xen/x86: rename acpi_scan_nodes to numa_scan_nodes Wei Chen
2021-09-24 0:40 ` Stefano Stabellini
2022-01-25 10:17 ` Jan Beulich
2022-01-27 8:14 ` Wei Chen
2021-09-23 12:02 ` [PATCH 16/37] xen/x86: export srat_bad to external Wei Chen
2021-09-24 0:41 ` Stefano Stabellini
2022-01-25 10:22 ` Jan Beulich
2022-01-27 8:35 ` Wei Chen
2022-01-27 8:37 ` Jan Beulich
2022-01-27 8:47 ` Wei Chen
2021-09-23 12:02 ` [PATCH 17/37] xen/x86: use CONFIG_NUMA to gate numa_scan_nodes Wei Chen
2021-09-24 0:41 ` Stefano Stabellini
2022-01-25 10:26 ` Jan Beulich
2022-01-27 8:37 ` Wei Chen
2021-09-23 12:02 ` [PATCH 18/37] xen: move NUMA common code from x86 to common Wei Chen
2021-09-23 12:02 ` [PATCH 19/37] xen/x86: promote VIRTUAL_BUG_ON to ASSERT in Wei Chen
2022-01-17 16:21 ` Jan Beulich
2022-01-18 7:52 ` Wei Chen
2021-09-23 12:02 ` [PATCH 20/37] xen: introduce CONFIG_EFI to stub API for non-EFI architecture Wei Chen
2021-09-24 1:15 ` Stefano Stabellini
2021-09-24 4:34 ` Wei Chen
2021-09-24 7:58 ` Jan Beulich
2021-09-24 10:31 ` Wei Chen
2021-09-24 10:49 ` Jan Beulich
2021-09-26 10:25 ` Wei Chen
2021-09-27 10:28 ` Wei Chen
2021-09-28 0:59 ` Stefano Stabellini
2021-09-28 4:16 ` Wei Chen
2021-09-28 5:01 ` Stefano Stabellini
2021-09-28 8:02 ` Jan Beulich
2021-10-03 23:28 ` Wei Chen
2022-01-25 10:34 ` Jan Beulich
2022-01-27 8:44 ` Wei Chen
2022-01-27 8:51 ` Wei Chen
2022-01-27 9:00 ` Jan Beulich
2022-01-27 9:09 ` Wei Chen
2022-01-27 9:16 ` Jan Beulich
2022-01-27 9:25 ` Wei Chen
2022-01-27 9:27 ` Jan Beulich
2022-01-27 10:00 ` Julien Grall
2022-01-28 4:35 ` Wei Chen
2021-09-23 12:02 ` [PATCH 21/37] xen/arm: Keep memory nodes in dtb for NUMA when boot from EFI Wei Chen
2021-09-24 1:23 ` Stefano Stabellini
2021-09-24 4:36 ` Wei Chen
2022-01-25 10:38 ` Jan Beulich
2022-01-27 8:45 ` Wei Chen
2021-09-23 12:02 ` [PATCH 22/37] xen/arm: use NR_MEM_BANKS to override default NR_NODE_MEMBLKS Wei Chen
2021-09-24 1:34 ` Stefano Stabellini
2021-09-26 13:13 ` Wei Chen
2021-09-27 3:25 ` Stefano Stabellini
2021-09-27 4:18 ` Wei Chen
2021-09-27 4:59 ` Stefano Stabellini
2021-09-27 6:25 ` Julien Grall
2021-09-27 6:46 ` Wei Chen
2021-09-27 6:53 ` Wei Chen
2021-09-27 7:35 ` Julien Grall
2021-09-27 10:21 ` Wei Chen
2021-09-27 10:39 ` Julien Grall
2021-09-27 16:58 ` Stefano Stabellini
2021-09-28 2:57 ` Wei Chen
2021-09-23 12:02 ` [PATCH 23/37] xen/arm: implement node distance helpers for Arm Wei Chen
2021-09-24 1:46 ` Stefano Stabellini
2021-09-24 4:41 ` Wei Chen
2021-09-24 19:36 ` Stefano Stabellini
2021-09-26 10:15 ` Wei Chen
2021-09-23 12:02 ` [PATCH 24/37] xen/arm: implement two arch helpers to get memory map info Wei Chen
2021-09-24 2:06 ` Stefano Stabellini
2021-09-24 4:42 ` Wei Chen
2021-09-23 12:02 ` [PATCH 25/37] xen/arm: implement bad_srat for Arm NUMA initialization Wei Chen
2021-09-24 2:09 ` Stefano Stabellini
2021-09-24 4:45 ` Wei Chen
2021-09-24 8:07 ` Jan Beulich
2021-09-24 19:33 ` Stefano Stabellini
2021-09-23 12:02 ` [PATCH 26/37] xen/arm: build NUMA cpu_to_node map in dt_smp_init_cpus Wei Chen
2021-09-24 2:26 ` Stefano Stabellini
2021-09-24 4:25 ` Wei Chen
2021-09-23 12:02 ` [PATCH 27/37] xen/arm: Add boot and secondary CPU to NUMA system Wei Chen
2021-09-23 12:02 ` [PATCH 28/37] xen/arm: stub memory hotplug access helpers for Arm Wei Chen
2021-09-24 2:33 ` Stefano Stabellini
2021-09-24 4:26 ` Wei Chen
2021-09-23 12:02 ` [PATCH 29/37] xen/arm: introduce a helper to parse device tree processor node Wei Chen
2021-09-24 2:44 ` Stefano Stabellini
2021-09-24 4:46 ` Wei Chen
2021-09-23 12:02 ` [PATCH 30/37] xen/arm: introduce a helper to parse device tree memory node Wei Chen
2021-09-24 3:05 ` Stefano Stabellini
2021-09-24 7:54 ` Wei Chen
2021-09-23 12:02 ` [PATCH 31/37] xen/arm: introduce a helper to parse device tree NUMA distance map Wei Chen
2021-09-24 3:05 ` Stefano Stabellini
2021-09-24 5:23 ` Wei Chen
2021-09-23 12:02 ` [PATCH 32/37] xen/arm: unified entry to parse all NUMA data from device tree Wei Chen
2021-09-24 3:16 ` Stefano Stabellini
2021-09-24 7:58 ` Wei Chen
2021-09-24 19:42 ` Stefano Stabellini
2021-09-23 12:02 ` [PATCH 33/37] xen/arm: keep guest still be NUMA unware Wei Chen
2021-09-24 3:19 ` Stefano Stabellini
2021-09-24 10:23 ` Wei Chen
2021-09-23 12:02 ` [PATCH 34/37] xen/arm: enable device tree based NUMA in system init Wei Chen
2021-09-24 3:28 ` Stefano Stabellini
2021-09-24 9:52 ` Wei Chen
2021-09-23 12:02 ` [PATCH 35/37] xen/arm: use CONFIG_NUMA to gate node_online_map in smpboot Wei Chen
2021-09-23 12:02 ` [PATCH 36/37] xen/arm: Provide Kconfig options for Arm to enable NUMA Wei Chen
2021-09-24 3:31 ` Stefano Stabellini
2021-09-24 10:13 ` Wei Chen
2021-09-24 19:39 ` Stefano Stabellini
2021-09-27 8:33 ` Jan Beulich
2021-09-27 8:45 ` Julien Grall
2021-09-27 9:17 ` Jan Beulich
2021-09-27 17:17 ` Stefano Stabellini
2021-09-28 2:59 ` Wei Chen
2021-09-28 3:30 ` Stefano Stabellini
2021-09-24 10:25 ` Jan Beulich
2021-09-24 10:37 ` Wei Chen
2021-09-23 12:02 ` [PATCH 37/37] docs: update numa command line to support Arm Wei Chen
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