On 6/22/2022 6:54 PM, Christoph Hellwig wrote:
Thanks,
this looks pretty good to me. A few comments below:
Thanks for your review.
On Fri, Jun 17, 2022 at 10:47:41AM -0400, Tianyu Lan wrote:
+/**
+ * struct io_tlb_area - IO TLB memory area descriptor
+ *
+ * This is a single area with a single lock.
+ *
+ * @used: The number of used IO TLB block.
+ * @index: The slot index to start searching in this area for next round.
+ * @lock: The lock to protect the above data structures in the map and
+ * unmap calls.
+ */
+struct io_tlb_area {
+ unsigned long used;
+ unsigned int index;
+ spinlock_t lock;
+};
This can go into swiotlb.c.
struct io_tlb_area is used in the struct io_tlb_mem.
+void __init swiotlb_adjust_nareas(unsigned int nareas);
And this should be marked static.
+#define DEFAULT_NUM_AREAS 1
I'd drop this define, the magic 1 and a > 1 comparism seems to
convey how it is used much better as the checks aren't about default
or not, but about larger than one.
I also think that we want some good way to size the default, e.g.
by number of CPUs or memory size.
swiotlb_adjust_nareas() is exposed to platforms to set area number.
When swiotlb_init() is called, smp_init() isn't called at that point and
so standard API of checking cpu number (e.g, num_online_cpus()) doesn't
work. Platforms may have other ways to get cpu number(e.g x86 may ACPI
MADT table entries to get cpu nubmer) and set area number. I will post
following patch to set cpu number via swiotlb_adjust_nareas(),
+void __init swiotlb_adjust_nareas(unsigned int nareas)
+{
+ if (!is_power_of_2(nareas)) {
+ pr_err("swiotlb: Invalid areas parameter %d.\n", nareas);
+ return;
+ }
+
+ default_nareas = nareas;
+
+ pr_info("area num %d.\n", nareas);
+ /* Round up number of slabs to the next power of 2.
+ * The last area is going be smaller than the rest if
+ * default_nslabs is not power of two.
+ */
Please follow the normal kernel comment style with a /* on its own line.
OK. Will update.
