| Message ID | 20171016054917.21577-1-aik@ozlabs.ru |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | [kernel] RFC: prom_init: Fetch flatten device tree from the system firmware | expand |
On Mon, Oct 16, 2017 at 04:49:17PM +1100, Alexey Kardashevskiy wrote: > At the moment, on 256CPU + 256 PCI devices guest, it takes the guest > about 8.5sec to read the entire device tree. Some explanation can be > found here: https://patchwork.ozlabs.org/patch/826124/ but mostly it is > because the kernel traverses the tree twice and it calls "getprop" for > each properly which is really SLOF as it searches from the linked list > beginning every time. > > Since SLOF has just learned to build FDT and this takes less than 0.5sec > for such a big guest, this makes use of the proposed client interface > method - "fdt-fetch". > > If "fdt-fetch" is not available, the old method is used. > > Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> I like the concept, few details though.. > --- > arch/powerpc/kernel/prom_init.c | 26 ++++++++++++++++++++++++++ > 1 file changed, 26 insertions(+) > > diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c > index 02190e90c7ae..daa50a153737 100644 > --- a/arch/powerpc/kernel/prom_init.c > +++ b/arch/powerpc/kernel/prom_init.c > @@ -2498,6 +2498,31 @@ static void __init flatten_device_tree(void) > prom_panic("Can't allocate initial device-tree chunk\n"); > mem_end = mem_start + room; > > + if (!call_prom_ret("fdt-fetch", 2, 1, NULL, mem_start, > + room - sizeof(mem_reserve_map))) { > + u32 size; > + > + hdr = (void *) mem_start; > + > + /* Fixup the boot cpuid */ > + hdr->boot_cpuid_phys = cpu_to_be32(prom.cpu); If SLOF is generating a tree it really should get this header field right as well. > + /* Append the reserved map to the end of the blob */ > + hdr->off_mem_rsvmap = hdr->totalsize; > + size = be32_to_cpu(hdr->totalsize); > + rsvmap = (void *) hdr + size; > + hdr->totalsize = cpu_to_be32(size + sizeof(mem_reserve_map)); > + memcpy(rsvmap, mem_reserve_map, sizeof(mem_reserve_map)); .. and the reserve map for that matter. I don't really understand what you're doing here. Note also that the reserve map is required to be 8-byte aligned, which totalsize might not be. > + /* Store the DT address */ > + dt_header_start = mem_start; > + > +#ifdef DEBUG_PROM > + prom_printf("Fetched DTB: %d bytes to @%x\n", size, mem_start); > +#endif > + goto print_exit; > + } > + > /* Get root of tree */ > root = call_prom("peer", 1, 1, (phandle)0); > if (root == (phandle)0) > @@ -2548,6 +2573,7 @@ static void __init flatten_device_tree(void) > /* Copy the reserve map in */ > memcpy(rsvmap, mem_reserve_map, sizeof(mem_reserve_map)); > > +print_exit: > #ifdef DEBUG_PROM > { > int i;
On 16/10/17 17:11, David Gibson wrote: > On Mon, Oct 16, 2017 at 04:49:17PM +1100, Alexey Kardashevskiy wrote: >> At the moment, on 256CPU + 256 PCI devices guest, it takes the guest >> about 8.5sec to read the entire device tree. Some explanation can be >> found here: https://patchwork.ozlabs.org/patch/826124/ but mostly it is >> because the kernel traverses the tree twice and it calls "getprop" for >> each properly which is really SLOF as it searches from the linked list >> beginning every time. >> >> Since SLOF has just learned to build FDT and this takes less than 0.5sec >> for such a big guest, this makes use of the proposed client interface >> method - "fdt-fetch". >> >> If "fdt-fetch" is not available, the old method is used. >> >> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> > > I like the concept, few details though.. > >> --- >> arch/powerpc/kernel/prom_init.c | 26 ++++++++++++++++++++++++++ >> 1 file changed, 26 insertions(+) >> >> diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c >> index 02190e90c7ae..daa50a153737 100644 >> --- a/arch/powerpc/kernel/prom_init.c >> +++ b/arch/powerpc/kernel/prom_init.c >> @@ -2498,6 +2498,31 @@ static void __init flatten_device_tree(void) >> prom_panic("Can't allocate initial device-tree chunk\n"); >> mem_end = mem_start + room; >> >> + if (!call_prom_ret("fdt-fetch", 2, 1, NULL, mem_start, >> + room - sizeof(mem_reserve_map))) { >> + u32 size; >> + >> + hdr = (void *) mem_start; >> + >> + /* Fixup the boot cpuid */ >> + hdr->boot_cpuid_phys = cpu_to_be32(prom.cpu); > > If SLOF is generating a tree it really should get this header field > right as well. Ah, I did not realize it is just a phandle from /chosen/cpu. Will fix. > >> + /* Append the reserved map to the end of the blob */ >> + hdr->off_mem_rsvmap = hdr->totalsize; >> + size = be32_to_cpu(hdr->totalsize); >> + rsvmap = (void *) hdr + size; >> + hdr->totalsize = cpu_to_be32(size + sizeof(mem_reserve_map)); >> + memcpy(rsvmap, mem_reserve_map, sizeof(mem_reserve_map)); > > .. and the reserve map for that matter. I don't really understand > what you're doing here. ? Get the blob, increase the FDT size by sizeof(mem_reserve_map), fix up totalsize and off_mem_rsvmap, copy mem_reserve_map to the end of the blob (the actual order is slightly different, may be a bit confusing). Asking SLOF to reserve the space seems to be unnecessary complication of the interface - SLOF does not provide any reserved memory records. > Note also that the reserve map is required to > be 8-byte aligned, which totalsize might not be. Ah, good point. > >> + /* Store the DT address */ >> + dt_header_start = mem_start; >> + >> +#ifdef DEBUG_PROM >> + prom_printf("Fetched DTB: %d bytes to @%x\n", size, mem_start); >> +#endif >> + goto print_exit; >> + } >> + >> /* Get root of tree */ >> root = call_prom("peer", 1, 1, (phandle)0); >> if (root == (phandle)0) >> @@ -2548,6 +2573,7 @@ static void __init flatten_device_tree(void) >> /* Copy the reserve map in */ >> memcpy(rsvmap, mem_reserve_map, sizeof(mem_reserve_map)); >> >> +print_exit: >> #ifdef DEBUG_PROM >> { >> int i; >
On Mon, Oct 16, 2017 at 05:22:55PM +1100, Alexey Kardashevskiy wrote: > On 16/10/17 17:11, David Gibson wrote: > > On Mon, Oct 16, 2017 at 04:49:17PM +1100, Alexey Kardashevskiy wrote: > >> At the moment, on 256CPU + 256 PCI devices guest, it takes the guest > >> about 8.5sec to read the entire device tree. Some explanation can be > >> found here: https://patchwork.ozlabs.org/patch/826124/ but mostly it is > >> because the kernel traverses the tree twice and it calls "getprop" for > >> each properly which is really SLOF as it searches from the linked list > >> beginning every time. > >> > >> Since SLOF has just learned to build FDT and this takes less than 0.5sec > >> for such a big guest, this makes use of the proposed client interface > >> method - "fdt-fetch". > >> > >> If "fdt-fetch" is not available, the old method is used. > >> > >> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> > > > > I like the concept, few details though.. > > > >> --- > >> arch/powerpc/kernel/prom_init.c | 26 ++++++++++++++++++++++++++ > >> 1 file changed, 26 insertions(+) > >> > >> diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c > >> index 02190e90c7ae..daa50a153737 100644 > >> --- a/arch/powerpc/kernel/prom_init.c > >> +++ b/arch/powerpc/kernel/prom_init.c > >> @@ -2498,6 +2498,31 @@ static void __init flatten_device_tree(void) > >> prom_panic("Can't allocate initial device-tree chunk\n"); > >> mem_end = mem_start + room; > >> > >> + if (!call_prom_ret("fdt-fetch", 2, 1, NULL, mem_start, > >> + room - sizeof(mem_reserve_map))) { > >> + u32 size; > >> + > >> + hdr = (void *) mem_start; > >> + > >> + /* Fixup the boot cpuid */ > >> + hdr->boot_cpuid_phys = cpu_to_be32(prom.cpu); > > > > If SLOF is generating a tree it really should get this header field > > right as well. > > > Ah, I did not realize it is just a phandle from /chosen/cpu. Will > fix. It's not a phandle. It's just the "address" (i.e. reg value) of the boot cpu. > >> + /* Append the reserved map to the end of the blob */ > >> + hdr->off_mem_rsvmap = hdr->totalsize; > >> + size = be32_to_cpu(hdr->totalsize); > >> + rsvmap = (void *) hdr + size; > >> + hdr->totalsize = cpu_to_be32(size + sizeof(mem_reserve_map)); > >> + memcpy(rsvmap, mem_reserve_map, sizeof(mem_reserve_map)); > > > > .. and the reserve map for that matter. I don't really understand > > what you're doing here. > > ? Get the blob, increase the FDT size by sizeof(mem_reserve_map), fix up > totalsize and off_mem_rsvmap, copy mem_reserve_map to the end of the blob > (the actual order is slightly different, may be a bit confusing). Right.. but where is mem_reserve_map coming from, if it hasn't come from an FDT? > Asking SLOF to reserve the space seems to be unnecessary complication of > the interface - SLOF does not provide any reserved memory records. Ah.. right, the reservations are coming from the pre-prom kernel, not from the firmware itself. Yeah, that makes sense. Ok, this makes sense then... > > Note also that the reserve map is required to > > be 8-byte aligned, which totalsize might not be. > > Ah, good point. ..at least with that fixed and maybe some comments to make what's gonig on clearer. > > > > > >> + /* Store the DT address */ > >> + dt_header_start = mem_start; > >> + > >> +#ifdef DEBUG_PROM > >> + prom_printf("Fetched DTB: %d bytes to @%x\n", size, mem_start); > >> +#endif > >> + goto print_exit; > >> + } > >> + > >> /* Get root of tree */ > >> root = call_prom("peer", 1, 1, (phandle)0); > >> if (root == (phandle)0) > >> @@ -2548,6 +2573,7 @@ static void __init flatten_device_tree(void) > >> /* Copy the reserve map in */ > >> memcpy(rsvmap, mem_reserve_map, sizeof(mem_reserve_map)); > >> > >> +print_exit: > >> #ifdef DEBUG_PROM > >> { > >> int i; > > > >
On 16/10/17 17:46, David Gibson wrote: > On Mon, Oct 16, 2017 at 05:22:55PM +1100, Alexey Kardashevskiy wrote: >> On 16/10/17 17:11, David Gibson wrote: >>> On Mon, Oct 16, 2017 at 04:49:17PM +1100, Alexey Kardashevskiy wrote: >>>> At the moment, on 256CPU + 256 PCI devices guest, it takes the guest >>>> about 8.5sec to read the entire device tree. Some explanation can be >>>> found here: https://patchwork.ozlabs.org/patch/826124/ but mostly it is >>>> because the kernel traverses the tree twice and it calls "getprop" for >>>> each properly which is really SLOF as it searches from the linked list >>>> beginning every time. >>>> >>>> Since SLOF has just learned to build FDT and this takes less than 0.5sec >>>> for such a big guest, this makes use of the proposed client interface >>>> method - "fdt-fetch". >>>> >>>> If "fdt-fetch" is not available, the old method is used. >>>> >>>> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> >>> >>> I like the concept, few details though.. >>> >>>> --- >>>> arch/powerpc/kernel/prom_init.c | 26 ++++++++++++++++++++++++++ >>>> 1 file changed, 26 insertions(+) >>>> >>>> diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c >>>> index 02190e90c7ae..daa50a153737 100644 >>>> --- a/arch/powerpc/kernel/prom_init.c >>>> +++ b/arch/powerpc/kernel/prom_init.c >>>> @@ -2498,6 +2498,31 @@ static void __init flatten_device_tree(void) >>>> prom_panic("Can't allocate initial device-tree chunk\n"); >>>> mem_end = mem_start + room; >>>> >>>> + if (!call_prom_ret("fdt-fetch", 2, 1, NULL, mem_start, >>>> + room - sizeof(mem_reserve_map))) { >>>> + u32 size; >>>> + >>>> + hdr = (void *) mem_start; >>>> + >>>> + /* Fixup the boot cpuid */ >>>> + hdr->boot_cpuid_phys = cpu_to_be32(prom.cpu); >>> >>> If SLOF is generating a tree it really should get this header field >>> right as well. >> >> >> Ah, I did not realize it is just a phandle from /chosen/cpu. Will >> fix. > > It's not a phandle. It's just the "address" (i.e. reg value) of the > boot cpu. Well, it is "reg" of a CPU with phandle==/chosen/cpu so my fdt code needs to look there to pick the right "reg" rather than just plain 0. I'll fix this but in general can it possibly be not a zero in QEMU/SLOF? > >>>> + /* Append the reserved map to the end of the blob */ >>>> + hdr->off_mem_rsvmap = hdr->totalsize; >>>> + size = be32_to_cpu(hdr->totalsize); >>>> + rsvmap = (void *) hdr + size; >>>> + hdr->totalsize = cpu_to_be32(size + sizeof(mem_reserve_map)); >>>> + memcpy(rsvmap, mem_reserve_map, sizeof(mem_reserve_map)); >>> >>> .. and the reserve map for that matter. I don't really understand >>> what you're doing here. >> >> ? Get the blob, increase the FDT size by sizeof(mem_reserve_map), fix up >> totalsize and off_mem_rsvmap, copy mem_reserve_map to the end of the blob >> (the actual order is slightly different, may be a bit confusing). > > Right.. but where is mem_reserve_map coming from, if it hasn't come > from an FDT? > >> Asking SLOF to reserve the space seems to be unnecessary complication of >> the interface - SLOF does not provide any reserved memory records. > > Ah.. right, the reservations are coming from the pre-prom kernel, not > from the firmware itself. Yeah, that makes sense. Ok, this makes > sense then... Right, the reservations are added via reserve_mem() in arch/powerpc/kernel/prom_init.c > >>> Note also that the reserve map is required to >>> be 8-byte aligned, which totalsize might not be. >> >> Ah, good point. > > ..at least with that fixed and maybe some comments to make what's > gonig on clearer. >> >> >>> >>>> + /* Store the DT address */ >>>> + dt_header_start = mem_start; >>>> + >>>> +#ifdef DEBUG_PROM >>>> + prom_printf("Fetched DTB: %d bytes to @%x\n", size, mem_start); >>>> +#endif >>>> + goto print_exit; >>>> + } >>>> + >>>> /* Get root of tree */ >>>> root = call_prom("peer", 1, 1, (phandle)0); >>>> if (root == (phandle)0) >>>> @@ -2548,6 +2573,7 @@ static void __init flatten_device_tree(void) >>>> /* Copy the reserve map in */ >>>> memcpy(rsvmap, mem_reserve_map, sizeof(mem_reserve_map)); >>>> >>>> +print_exit: >>>> #ifdef DEBUG_PROM >>>> { >>>> int i; >>> >> >> > > > >
On Mon, Oct 16, 2017 at 06:07:06PM +1100, Alexey Kardashevskiy wrote: > On 16/10/17 17:46, David Gibson wrote: > > On Mon, Oct 16, 2017 at 05:22:55PM +1100, Alexey Kardashevskiy wrote: > >> On 16/10/17 17:11, David Gibson wrote: > >>> On Mon, Oct 16, 2017 at 04:49:17PM +1100, Alexey Kardashevskiy wrote: > >>>> At the moment, on 256CPU + 256 PCI devices guest, it takes the guest > >>>> about 8.5sec to read the entire device tree. Some explanation can be > >>>> found here: https://patchwork.ozlabs.org/patch/826124/ but mostly it is > >>>> because the kernel traverses the tree twice and it calls "getprop" for > >>>> each properly which is really SLOF as it searches from the linked list > >>>> beginning every time. > >>>> > >>>> Since SLOF has just learned to build FDT and this takes less than 0.5sec > >>>> for such a big guest, this makes use of the proposed client interface > >>>> method - "fdt-fetch". > >>>> > >>>> If "fdt-fetch" is not available, the old method is used. > >>>> > >>>> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> > >>> > >>> I like the concept, few details though.. > >>> > >>>> --- > >>>> arch/powerpc/kernel/prom_init.c | 26 ++++++++++++++++++++++++++ > >>>> 1 file changed, 26 insertions(+) > >>>> > >>>> diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c > >>>> index 02190e90c7ae..daa50a153737 100644 > >>>> --- a/arch/powerpc/kernel/prom_init.c > >>>> +++ b/arch/powerpc/kernel/prom_init.c > >>>> @@ -2498,6 +2498,31 @@ static void __init flatten_device_tree(void) > >>>> prom_panic("Can't allocate initial device-tree chunk\n"); > >>>> mem_end = mem_start + room; > >>>> > >>>> + if (!call_prom_ret("fdt-fetch", 2, 1, NULL, mem_start, > >>>> + room - sizeof(mem_reserve_map))) { > >>>> + u32 size; > >>>> + > >>>> + hdr = (void *) mem_start; > >>>> + > >>>> + /* Fixup the boot cpuid */ > >>>> + hdr->boot_cpuid_phys = cpu_to_be32(prom.cpu); > >>> > >>> If SLOF is generating a tree it really should get this header field > >>> right as well. > >> > >> > >> Ah, I did not realize it is just a phandle from /chosen/cpu. Will > >> fix. > > > > It's not a phandle. It's just the "address" (i.e. reg value) of the > > boot cpu. > > > Well, it is "reg" of a CPU with phandle==/chosen/cpu so my fdt code needs > to look there to pick the right "reg" rather than just plain 0. Ah, right, I see what you mean. > I'll fix > this but in general can it possibly be not a zero in QEMU/SLOF? Erm.. probably not, but I'm not totally certain what could happen if you tried creating all your cpu cores explicitly with -device instead of just using -smp. I think it's safer to look it up in SLOF, so that it won't break if we change how cpu addresses are assigned in qemu.
On Mon, Oct 16, 2017 at 06:07:06PM +1100, Alexey Kardashevskiy wrote: > On 16/10/17 17:46, David Gibson wrote: > >>>> + /* Fixup the boot cpuid */ > >>>> + hdr->boot_cpuid_phys = cpu_to_be32(prom.cpu); > >>> > >>> If SLOF is generating a tree it really should get this header field > >>> right as well. > >> > >> > >> Ah, I did not realize it is just a phandle from /chosen/cpu. Will > >> fix. > > > > It's not a phandle. It's just the "address" (i.e. reg value) of the > > boot cpu. > > Well, it is "reg" of a CPU with phandle==/chosen/cpu so my fdt code needs > to look there to pick the right "reg" rather than just plain 0. I'll fix > this but in general can it possibly be not a zero in QEMU/SLOF? /chosen/cpu is an ihandle, not a phandle. Most (if not all) references in /chosen are. Segher
On 16/10/17 21:20, Segher Boessenkool wrote: > On Mon, Oct 16, 2017 at 06:07:06PM +1100, Alexey Kardashevskiy wrote: >> On 16/10/17 17:46, David Gibson wrote: > >>>>>> + /* Fixup the boot cpuid */ >>>>>> + hdr->boot_cpuid_phys = cpu_to_be32(prom.cpu); >>>>> >>>>> If SLOF is generating a tree it really should get this header field >>>>> right as well. >>>> >>>> >>>> Ah, I did not realize it is just a phandle from /chosen/cpu. Will >>>> fix. >>> >>> It's not a phandle. It's just the "address" (i.e. reg value) of the >>> boot cpu. >> >> Well, it is "reg" of a CPU with phandle==/chosen/cpu so my fdt code needs >> to look there to pick the right "reg" rather than just plain 0. I'll fix >> this but in general can it possibly be not a zero in QEMU/SLOF? > > /chosen/cpu is an ihandle, not a phandle. Sure, that is what my proposed fdt-boot-cpu does already. > Most (if not all) references > in /chosen are.
Alexey Kardashevskiy <aik@ozlabs.ru> writes: > At the moment, on 256CPU + 256 PCI devices guest, it takes the guest > about 8.5sec to read the entire device tree. Some explanation can be > found here: https://patchwork.ozlabs.org/patch/826124/ but mostly it is > because the kernel traverses the tree twice and it calls "getprop" for > each properly which is really SLOF as it searches from the linked list > beginning every time. > > Since SLOF has just learned to build FDT and this takes less than 0.5sec > for such a big guest, this makes use of the proposed client interface > method - "fdt-fetch". It's a pity doing it the normal way is so slow, but this seems like a reasonable idea anyway. > diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c > index 02190e90c7ae..daa50a153737 100644 > --- a/arch/powerpc/kernel/prom_init.c > +++ b/arch/powerpc/kernel/prom_init.c > @@ -2498,6 +2498,31 @@ static void __init flatten_device_tree(void) > prom_panic("Can't allocate initial device-tree chunk\n"); > mem_end = mem_start + room; I'd prefer you didn't munge it inside flatten_device_tree(), rather create a wrapper that does ~=: void get_flat_devicetree(void) { if (!fetch_flat_devicetree()) flatten_device_tree(); printf(...) } > + if (!call_prom_ret("fdt-fetch", 2, 1, NULL, mem_start, > + room - sizeof(mem_reserve_map))) { > + u32 size; > + > + hdr = (void *) mem_start; > + > + /* Fixup the boot cpuid */ > + hdr->boot_cpuid_phys = cpu_to_be32(prom.cpu); > + > + /* Append the reserved map to the end of the blob */ > + hdr->off_mem_rsvmap = hdr->totalsize; > + size = be32_to_cpu(hdr->totalsize); > + rsvmap = (void *) hdr + size; > + hdr->totalsize = cpu_to_be32(size + sizeof(mem_reserve_map)); > + memcpy(rsvmap, mem_reserve_map, sizeof(mem_reserve_map)); > + > + /* Store the DT address */ > + dt_header_start = mem_start; > + > +#ifdef DEBUG_PROM > + prom_printf("Fetched DTB: %d bytes to @%x\n", size, mem_start); > +#endif I think that should actually not be under DEBUG_PROM. The origin of the FDT is fairly crucial information, so I think we can tolerate an extra line of output to know that. > + goto print_exit; This was the clue that it should be in a separate function :) cheers > + } > + > /* Get root of tree */ > root = call_prom("peer", 1, 1, (phandle)0); > if (root == (phandle)0) > @@ -2548,6 +2573,7 @@ static void __init flatten_device_tree(void) > /* Copy the reserve map in */ > memcpy(rsvmap, mem_reserve_map, sizeof(mem_reserve_map)); > > +print_exit: > #ifdef DEBUG_PROM > { > int i; > -- > 2.11.0
diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c index 02190e90c7ae..daa50a153737 100644 --- a/arch/powerpc/kernel/prom_init.c +++ b/arch/powerpc/kernel/prom_init.c @@ -2498,6 +2498,31 @@ static void __init flatten_device_tree(void) prom_panic("Can't allocate initial device-tree chunk\n"); mem_end = mem_start + room; + if (!call_prom_ret("fdt-fetch", 2, 1, NULL, mem_start, + room - sizeof(mem_reserve_map))) { + u32 size; + + hdr = (void *) mem_start; + + /* Fixup the boot cpuid */ + hdr->boot_cpuid_phys = cpu_to_be32(prom.cpu); + + /* Append the reserved map to the end of the blob */ + hdr->off_mem_rsvmap = hdr->totalsize; + size = be32_to_cpu(hdr->totalsize); + rsvmap = (void *) hdr + size; + hdr->totalsize = cpu_to_be32(size + sizeof(mem_reserve_map)); + memcpy(rsvmap, mem_reserve_map, sizeof(mem_reserve_map)); + + /* Store the DT address */ + dt_header_start = mem_start; + +#ifdef DEBUG_PROM + prom_printf("Fetched DTB: %d bytes to @%x\n", size, mem_start); +#endif + goto print_exit; + } + /* Get root of tree */ root = call_prom("peer", 1, 1, (phandle)0); if (root == (phandle)0) @@ -2548,6 +2573,7 @@ static void __init flatten_device_tree(void) /* Copy the reserve map in */ memcpy(rsvmap, mem_reserve_map, sizeof(mem_reserve_map)); +print_exit: #ifdef DEBUG_PROM { int i;
At the moment, on 256CPU + 256 PCI devices guest, it takes the guest about 8.5sec to read the entire device tree. Some explanation can be found here: https://patchwork.ozlabs.org/patch/826124/ but mostly it is because the kernel traverses the tree twice and it calls "getprop" for each properly which is really SLOF as it searches from the linked list beginning every time. Since SLOF has just learned to build FDT and this takes less than 0.5sec for such a big guest, this makes use of the proposed client interface method - "fdt-fetch". If "fdt-fetch" is not available, the old method is used. Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> --- arch/powerpc/kernel/prom_init.c | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+)