Re: [RFC PATCH V4 1/1] swiotlb: Split up single swiotlb lock

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



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.



[Index of Archives]     [Linux Samsung SoC]     [Linux Rockchip SoC]     [Linux Actions SoC]     [Linux for Synopsys ARC Processors]     [Linux NFS]     [Linux NILFS]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]


  Powered by Linux