RE: [PATCH v5] modify the IO_TLB_SEGSIZE and IO_TLB_DEFAULT_SIZE configurable as flexible requirement about SW-IOMMU.
From: Wang, Xiaoming
Date: Wed Mar 04 2015 - 22:54:22 EST
> -----Original Message-----
> From: Konrad Rzeszutek Wilk [mailto:konrad.wilk@xxxxxxxxxx]
> Sent: Thursday, March 5, 2015 3:43 AM
> To: Wang, Xiaoming
> Cc: chris@xxxxxxxxxxxxxxxxxx; david.vrabel@xxxxxxxxxx;
> lauraa@xxxxxxxxxxxxxx; heiko.carstens@xxxxxxxxxx; linux@xxxxxxxxxxx;
> Liu@xxxxxxxxxxxxxxxxxxxx; Liu, Chuansheng; Zhang@xxxxxxxxxxxxxxxxxxxx;
> Zhang, Dongxing; takahiro.akashi@xxxxxxxxxx; akpm@xxxxxxxxxxxxxxxxxxxx;
> linux-mips@xxxxxxxxxxxxxx; ralf@xxxxxxxxxxxxxx; xen-
> devel@xxxxxxxxxxxxxxxxxxxx; boris.ostrovsky@xxxxxxxxxx;
> d.kasatkin@xxxxxxxxxxx; pebolle@xxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> JBeulich@xxxxxxxx
> Subject: Re: [PATCH v5] modify the IO_TLB_SEGSIZE and
> IO_TLB_DEFAULT_SIZE configurable as flexible requirement about SW-
> IOMMU.
>
> On Tue, Mar 03, 2015 at 04:11:09PM +0800, Wang Xiaoming wrote:
> > The maximum of SW-IOMMU is limited to 2^11*128 = 256K.
> > And the size of IO_TLB_DEFAULT_SIZE is limited to (64UL<<20) 64M now.
> > While in different platform and different requirement this seems improper.
> > So modifing the IO_TLB_SEGSIZE to io_tlb_segsize and
> > IO_TLB_DEFAULT_SIZE to io_tlb_default_size which can configure by
> kernel cmdline.
> > This can meet different requirement.
> >
> > Signed-off-by: Chuansheng Liu <chuansheng.liu@xxxxxxxxx>
> > Signed-off-by: Zhang Dongxing <dongxing.zhang@xxxxxxxxx>
> > Signed-off-by: Wang Xiaoming <xiaoming.wang@xxxxxxxxx>
> > ---
> > patch v1 make this change at Kconfig
> > which needs to edit the .config manually.
> > https://lkml.org/lkml/2015/1/25/571
> >
> > patch v2 only change IO_TLB_SEGSIZE configurable.
> > https://lkml.org/lkml/2015/2/5/812
> >
> > patch v3 parsing io_tlb_segsize and
> > io_tlb_default_size independently.
> > https://lkml.org/lkml/2015/2/15/217
> >
> > patch v4 hasn't validated the data from command line.
>
> Thank you for redoing this per review.
>
> > https://lkml.org/lkml/2015/2/17/114
> >
> > Documentation/kernel-parameters.txt | 9 ++++-
> > arch/mips/cavium-octeon/dma-octeon.c | 2 +-
> > arch/mips/netlogic/common/nlm-dma.c | 2 +-
> > drivers/xen/swiotlb-xen.c | 6 +--
> > include/linux/swiotlb.h | 8 +---
> > lib/swiotlb.c | 68 +++++++++++++++++++++++++---------
> > 6 files changed, 65 insertions(+), 30 deletions(-)
> >
> > diff --git a/Documentation/kernel-parameters.txt
> > b/Documentation/kernel-parameters.txt
> > index 4df73da..1f50e86 100644
> > --- a/Documentation/kernel-parameters.txt
> > +++ b/Documentation/kernel-parameters.txt
> > @@ -3438,10 +3438,17 @@ bytes respectively. Such letter suffixes can
> also be entirely omitted.
> > it if 0 is given (See
> Documentation/cgroups/memory.txt)
> >
> > swiotlb= [ARM,IA-64,PPC,MIPS,X86]
> > - Format: { <int> | force }
> > + Format: { <int> | force | <int> | <int>}
> ,
>
> s/|/,/
>
How about change the Format to
Format: { <int>,force,<int>,<int>}
Force the parameter input in consecutive order.
> > <int> -- Number of I/O TLB slabs
> > force -- force using of bounce buffers even if they
> > wouldn't be automatically used by the kernel
> > + <int> -- Maximum allowable number of contiguous
> slabs to map
> > + <int> -- The size of SW-MMU mapped.
> > + Using "," to separate them one by one.
>
> "Use ',' to seperate them."
>
> > + Example:
> > + BOARD_KERNEL_CMDLINE +=
> swiotlb=32768,force,512,268435456
> > + io_tlb_nslabs=32768, swiotlb_force=1,
> > + io_tlb_segsize=512, io_tlb_default_size=268435456
>
> I think you can remove the example - and just have it in the C code.
>
> >
> > switches= [HW,M68k]
> >
> > diff --git a/arch/mips/cavium-octeon/dma-octeon.c
> > b/arch/mips/cavium-octeon/dma-octeon.c
> > index 3778655..a521af6 100644
> > --- a/arch/mips/cavium-octeon/dma-octeon.c
> > +++ b/arch/mips/cavium-octeon/dma-octeon.c
> > @@ -312,7 +312,7 @@ void __init plat_swiotlb_setup(void)
> > swiotlbsize = 64 * (1<<20);
> > #endif
> > swiotlb_nslabs = swiotlbsize >> IO_TLB_SHIFT;
> > - swiotlb_nslabs = ALIGN(swiotlb_nslabs, IO_TLB_SEGSIZE);
> > + swiotlb_nslabs = ALIGN(swiotlb_nslabs, io_tlb_segsize);
> > swiotlbsize = swiotlb_nslabs << IO_TLB_SHIFT;
> >
> > octeon_swiotlb = alloc_bootmem_low_pages(swiotlbsize);
> > diff --git a/arch/mips/netlogic/common/nlm-dma.c
> > b/arch/mips/netlogic/common/nlm-dma.c
> > index f3d4ae8..eeffa8f 100644
> > --- a/arch/mips/netlogic/common/nlm-dma.c
> > +++ b/arch/mips/netlogic/common/nlm-dma.c
> > @@ -99,7 +99,7 @@ void __init plat_swiotlb_setup(void)
> >
> > swiotlbsize = 1 << 20; /* 1 MB for now */
> > swiotlb_nslabs = swiotlbsize >> IO_TLB_SHIFT;
> > - swiotlb_nslabs = ALIGN(swiotlb_nslabs, IO_TLB_SEGSIZE);
> > + swiotlb_nslabs = ALIGN(swiotlb_nslabs, io_tlb_segsize);
> > swiotlbsize = swiotlb_nslabs << IO_TLB_SHIFT;
> >
> > nlm_swiotlb = alloc_bootmem_low_pages(swiotlbsize);
> > diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
> > index 810ad41..3b3e9fe 100644
> > --- a/drivers/xen/swiotlb-xen.c
> > +++ b/drivers/xen/swiotlb-xen.c
> > @@ -164,11 +164,11 @@ xen_swiotlb_fixup(void *buf, size_t size,
> unsigned long nslabs)
> > dma_addr_t dma_handle;
> > phys_addr_t p = virt_to_phys(buf);
> >
> > - dma_bits = get_order(IO_TLB_SEGSIZE << IO_TLB_SHIFT) +
> PAGE_SHIFT;
> > + dma_bits = get_order(io_tlb_segsize << IO_TLB_SHIFT) + PAGE_SHIFT;
> >
> > i = 0;
> > do {
> > - int slabs = min(nslabs - i, (unsigned long)IO_TLB_SEGSIZE);
> > + int slabs = min(nslabs - i, (unsigned long)io_tlb_segsize);
> >
> > do {
> > rc = xen_create_contiguous_region( @@ -187,7
> +187,7 @@ static
> > unsigned long xen_set_nslabs(unsigned long nr_tbl) {
> > if (!nr_tbl) {
> > xen_io_tlb_nslabs = (64 * 1024 * 1024 >> IO_TLB_SHIFT);
> > - xen_io_tlb_nslabs = ALIGN(xen_io_tlb_nslabs,
> IO_TLB_SEGSIZE);
> > + xen_io_tlb_nslabs = ALIGN(xen_io_tlb_nslabs, io_tlb_segsize);
> > } else
> > xen_io_tlb_nslabs = nr_tbl;
> >
> > diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h index
> > e7a018e..13506db 100644
> > --- a/include/linux/swiotlb.h
> > +++ b/include/linux/swiotlb.h
> > @@ -8,13 +8,7 @@ struct dma_attrs;
> > struct scatterlist;
> >
> > extern int swiotlb_force;
> > -
> > -/*
> > - * Maximum allowable number of contiguous slabs to map,
> > - * must be a power of 2. What is the appropriate value ?
> > - * The complexity of {map,unmap}_single is linearly dependent on this
> value.
> > - */
> > -#define IO_TLB_SEGSIZE 128
> > +extern int io_tlb_segsize;
> >
> > /*
> > * log of the size of each IO TLB slab. The number of slabs is
> > command line diff --git a/lib/swiotlb.c b/lib/swiotlb.c index
> > 4abda07..3b71afd 100644
> > --- a/lib/swiotlb.c
> > +++ b/lib/swiotlb.c
> > @@ -56,6 +56,24 @@
> > int swiotlb_force;
> >
> > /*
> > + * default to 128
> > + * Maximum allowable number of contiguous slabs to map,
> > + * must be a power of 2. What is the appropriate value ?
> > + * define io_tlb_segsize as a parameter
> > + * which can be changed dynamically in config file for special usage.
> > + * The complexity of {map,unmap}_single is linearly dependent on this
> value.
> > + */
> > +#define IO_TLB_SEGSIZE 128
>
> Add the tab back please.
>
> > +int io_tlb_segsize = IO_TLB_SEGSIZE;
> > +
> > +/* default to 64MB
> > + * define io_tlb_default_size as a parameter
> > + * which can be changed dynamically in config file for special usage.
>
> .. or as a parameter during bootup.
>
> > + */
> > +#define IO_TLB_DEFAULT_SIZE (64UL<<20) static unsigned long
> > +io_tlb_default_size = IO_TLB_DEFAULT_SIZE;
> > +
> > +/*
> > * Used to do a quick range check in swiotlb_tbl_unmap_single and
> > * swiotlb_tbl_sync_single_*, to see if the memory was in fact allocated by
> this
> > * API.
> > @@ -101,13 +119,32 @@ setup_io_tlb_npages(char *str) {
> > if (isdigit(*str)) {
> > io_tlb_nslabs = simple_strtoul(str, &str, 0);
> > - /* avoid tail segment of size < IO_TLB_SEGSIZE */
> > - io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
> > }
> > if (*str == ',')
> > ++str;
> > - if (!strcmp(str, "force"))
> > + if (!strncmp(str, "force", 5)) {
> > swiotlb_force = 1;
> > + str += 5;
> > + }
>
> So the format is now:
>
> Format: { <int> | force | <int> | <int>}
>
> which means I can do
> 32,22323,force
>
> Or
> force,32
>
> Or
> 32,force
>
If I use Format: { <int>,force,<int>,<int>}
32,22323,force can't acceptable.
There are three <int> here, if there are out of order, that will cause confuse.
Only 32,force,32323
Or 32,,32323,2322
Or ,,323222,3232
Are available.
> I think you need to make function be inside a loop to deal with 'force' being
> at odd locations.
>
> > + if (*str == ',')
> > + ++str;
> > + if (isdigit(*str)) {
> > + int n = 0;
> > + io_tlb_segsize = simple_strtoul(str, &str, 0);
> > + io_tlb_segsize = ALIGN(io_tlb_segsize, IO_TLB_SEGSIZE);
> > + while ((io_tlb_segsize - 1) >> n)
> > + n++;
> > + io_tlb_segsize = (1 << n);
> > + }
> > + if (*str == ',')
> > + ++str;
> > + if (isdigit(*str)) {
> > + io_tlb_default_size = simple_strtoul(str, &str, 0);
> > + io_tlb_default_size = ALIGN(io_tlb_default_size,
> IO_TLB_DEFAULT_SIZE);
> > + }
> > +
> > + /* avoid tail segment of size < io_tlb_segsize */
> > + io_tlb_nslabs = ALIGN(io_tlb_nslabs, io_tlb_segsize);
> >
Here has a leakage if io_tlb_nslabs hasn't set before it will be set to io_tlb_segsize.
I will fix it in next version.
> > return 0;
> > }
> > @@ -120,15 +157,13 @@ unsigned long swiotlb_nr_tbl(void) }
> > EXPORT_SYMBOL_GPL(swiotlb_nr_tbl);
> >
> > -/* default to 64MB */
> > -#define IO_TLB_DEFAULT_SIZE (64UL<<20) unsigned long
> > swiotlb_size_or_default(void) {
> > unsigned long size;
> >
> > size = io_tlb_nslabs << IO_TLB_SHIFT;
> >
> > - return size ? size : (IO_TLB_DEFAULT_SIZE);
> > + return size ? size : (io_tlb_default_size);
> > }
> >
> > /* Note that this doesn't work with highmem page */ @@ -183,7 +218,7
> > @@ int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs,
> > int verbose)
> >
> > /*
> > * Allocate and initialize the free list array. This array is used
> > - * to find contiguous free memory regions of size up to
> IO_TLB_SEGSIZE
> > + * to find contiguous free memory regions of size up to
> > +io_tlb_segsize
> > * between io_tlb_start and io_tlb_end.
> > */
> > io_tlb_list = memblock_virt_alloc(
> > @@ -193,7 +228,7 @@ int __init swiotlb_init_with_tbl(char *tlb, unsigned
> long nslabs, int verbose)
> > PAGE_ALIGN(io_tlb_nslabs *
> sizeof(phys_addr_t)),
> > PAGE_SIZE);
> > for (i = 0; i < io_tlb_nslabs; i++) {
> > - io_tlb_list[i] = IO_TLB_SEGSIZE - OFFSET(i, IO_TLB_SEGSIZE);
> > + io_tlb_list[i] = io_tlb_segsize - OFFSET(i, io_tlb_segsize);
> > io_tlb_orig_addr[i] = INVALID_PHYS_ADDR;
> > }
> > io_tlb_index = 0;
> > @@ -211,13 +246,12 @@ int __init swiotlb_init_with_tbl(char *tlb,
> > unsigned long nslabs, int verbose) void __init swiotlb_init(int
> > verbose) {
> > - size_t default_size = IO_TLB_DEFAULT_SIZE;
> > unsigned char *vstart;
> > unsigned long bytes;
> >
> > if (!io_tlb_nslabs) {
> > - io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
> > - io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
> > + io_tlb_nslabs = (io_tlb_default_size >> IO_TLB_SHIFT);
> > + io_tlb_nslabs = ALIGN(io_tlb_nslabs, io_tlb_segsize);
> > }
> >
> > bytes = io_tlb_nslabs << IO_TLB_SHIFT; @@ -249,7 +283,7 @@
> > swiotlb_late_init_with_default_size(size_t default_size)
> >
> > if (!io_tlb_nslabs) {
> > io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
> > - io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
> > + io_tlb_nslabs = ALIGN(io_tlb_nslabs, io_tlb_segsize);
> > }
> >
> > /*
> > @@ -308,7 +342,7 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned
> > long nslabs)
> >
> > /*
> > * Allocate and initialize the free list array. This array is used
> > - * to find contiguous free memory regions of size up to
> IO_TLB_SEGSIZE
> > + * to find contiguous free memory regions of size up to
> > +io_tlb_segsize
> > * between io_tlb_start and io_tlb_end.
> > */
> > io_tlb_list = (unsigned int *)__get_free_pages(GFP_KERNEL, @@ -
> 324,7
> > +358,7 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
> > goto cleanup4;
> >
> > for (i = 0; i < io_tlb_nslabs; i++) {
> > - io_tlb_list[i] = IO_TLB_SEGSIZE - OFFSET(i, IO_TLB_SEGSIZE);
> > + io_tlb_list[i] = io_tlb_segsize - OFFSET(i, io_tlb_segsize);
> > io_tlb_orig_addr[i] = INVALID_PHYS_ADDR;
> > }
> > io_tlb_index = 0;
> > @@ -493,7 +527,7 @@ phys_addr_t swiotlb_tbl_map_single(struct device
> > *hwdev,
> >
> > for (i = index; i < (int) (index + nslots); i++)
> > io_tlb_list[i] = 0;
> > - for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) !=
> IO_TLB_SEGSIZE - 1) && io_tlb_list[i]; i--)
> > + for (i = index - 1; (OFFSET(i, io_tlb_segsize) !=
> io_tlb_segsize -
> > +1) && io_tlb_list[i]; i--)
> > io_tlb_list[i] = ++count;
> > tlb_addr = io_tlb_start + (index << IO_TLB_SHIFT);
> >
> > @@ -571,7 +605,7 @@ void swiotlb_tbl_unmap_single(struct device
> *hwdev, phys_addr_t tlb_addr,
> > */
> > spin_lock_irqsave(&io_tlb_lock, flags);
> > {
> > - count = ((index + nslots) < ALIGN(index + 1, IO_TLB_SEGSIZE) ?
> > + count = ((index + nslots) < ALIGN(index + 1, io_tlb_segsize) ?
> > io_tlb_list[index + nslots] : 0);
> > /*
> > * Step 1: return the slots to the free list, merging the @@ -
> 585,7
> > +619,7 @@ void swiotlb_tbl_unmap_single(struct device *hwdev,
> phys_addr_t tlb_addr,
> > * Step 2: merge the returned slots with the preceding slots,
> > * if available (non zero)
> > */
> > - for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) !=
> IO_TLB_SEGSIZE -1) && io_tlb_list[i]; i--)
> > + for (i = index - 1; (OFFSET(i, io_tlb_segsize) != io_tlb_segsize
> > +-1) && io_tlb_list[i]; i--)
> > io_tlb_list[i] = ++count;
> > }
> > spin_unlock_irqrestore(&io_tlb_lock, flags);
> > --
> > 1.7.9.5
> >
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