| Message ID | 20190815041057.13627-5-alastair@au1.ibm.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | powerpc: convert cache asm to C | expand |
| Context | Check | Description |
|---|---|---|
| snowpatch_ozlabs/apply_patch | success | Successfully applied on branch next (da206bd46848568e1aaf35f00e2d78bf9bc94f95) |
| snowpatch_ozlabs/checkpatch | warning | total: 0 errors, 2 warnings, 0 checks, 45 lines checked |
On Thu, Aug 15, 2019 at 02:10:49PM +1000, Alastair D'Silva wrote: > From: Alastair D'Silva <alastair@d-silva.org> > > When presented with large amounts of memory being hotplugged > (in my test case, ~890GB), the call to flush_dcache_range takes > a while (~50 seconds), triggering RCU stalls. > > This patch breaks up the call into 16GB chunks, calling > cond_resched() inbetween to allow the scheduler to run. > > Signed-off-by: Alastair D'Silva <alastair@d-silva.org> > --- > arch/powerpc/mm/mem.c | 16 ++++++++++++++-- > 1 file changed, 14 insertions(+), 2 deletions(-) > > diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c > index 5400da87a804..fb0d5e9aa11b 100644 > --- a/arch/powerpc/mm/mem.c > +++ b/arch/powerpc/mm/mem.c > @@ -104,11 +104,14 @@ int __weak remove_section_mapping(unsigned long start, unsigned long end) > return -ENODEV; > } > > +#define FLUSH_CHUNK_SIZE (16ull * 1024ull * 1024ull * 1024ull) IMHO this begs for adding SZ_16G to include/linux/sizes.h and using it here > + > int __ref arch_add_memory(int nid, u64 start, u64 size, > struct mhp_restrictions *restrictions) > { > unsigned long start_pfn = start >> PAGE_SHIFT; > unsigned long nr_pages = size >> PAGE_SHIFT; > + unsigned long i; > int rc; > > resize_hpt_for_hotplug(memblock_phys_mem_size()); > @@ -120,7 +123,11 @@ int __ref arch_add_memory(int nid, u64 start, u64 size, > start, start + size, rc); > return -EFAULT; > } > - flush_dcache_range(start, start + size); > + > + for (i = 0; i < size; i += FLUSH_CHUNK_SIZE) { > + flush_dcache_range(start + i, min(start + size, start + i + FLUSH_CHUNK_SIZE)); > + cond_resched(); > + } > > return __add_pages(nid, start_pfn, nr_pages, restrictions); > } > @@ -131,13 +138,18 @@ void __ref arch_remove_memory(int nid, u64 start, u64 size, > unsigned long start_pfn = start >> PAGE_SHIFT; > unsigned long nr_pages = size >> PAGE_SHIFT; > struct page *page = pfn_to_page(start_pfn) + vmem_altmap_offset(altmap); > + unsigned long i; > int ret; > > __remove_pages(page_zone(page), start_pfn, nr_pages, altmap); > > /* Remove htab bolted mappings for this section of memory */ > start = (unsigned long)__va(start); > - flush_dcache_range(start, start + size); > + for (i = 0; i < size; i += FLUSH_CHUNK_SIZE) { > + flush_dcache_range(start + i, min(start + size, start + i + FLUSH_CHUNK_SIZE)); > + cond_resched(); > + } > + > ret = remove_section_mapping(start, start + size); > WARN_ON_ONCE(ret); > > -- > 2.21.0 >
Le 15/08/2019 à 06:10, Alastair D'Silva a écrit : > From: Alastair D'Silva <alastair@d-silva.org> > > When presented with large amounts of memory being hotplugged > (in my test case, ~890GB), the call to flush_dcache_range takes > a while (~50 seconds), triggering RCU stalls. > > This patch breaks up the call into 16GB chunks, calling > cond_resched() inbetween to allow the scheduler to run. Is 16GB small enough ? If 890GB takes 50s, 16GB still takes about 1s. I'd use 1GB chuncks to remain below 100ms. > > Signed-off-by: Alastair D'Silva <alastair@d-silva.org> > --- > arch/powerpc/mm/mem.c | 16 ++++++++++++++-- > 1 file changed, 14 insertions(+), 2 deletions(-) > > diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c > index 5400da87a804..fb0d5e9aa11b 100644 > --- a/arch/powerpc/mm/mem.c > +++ b/arch/powerpc/mm/mem.c > @@ -104,11 +104,14 @@ int __weak remove_section_mapping(unsigned long start, unsigned long end) > return -ENODEV; > } > > +#define FLUSH_CHUNK_SIZE (16ull * 1024ull * 1024ull * 1024ull) Can we use SZ_16GB ? > + > int __ref arch_add_memory(int nid, u64 start, u64 size, > struct mhp_restrictions *restrictions) > { > unsigned long start_pfn = start >> PAGE_SHIFT; > unsigned long nr_pages = size >> PAGE_SHIFT; > + unsigned long i; > int rc; > > resize_hpt_for_hotplug(memblock_phys_mem_size()); > @@ -120,7 +123,11 @@ int __ref arch_add_memory(int nid, u64 start, u64 size, > start, start + size, rc); > return -EFAULT; > } > - flush_dcache_range(start, start + size); > + > + for (i = 0; i < size; i += FLUSH_CHUNK_SIZE) { > + flush_dcache_range(start + i, min(start + size, start + i + FLUSH_CHUNK_SIZE)); Isn't the line a bit long (I have not checked). > + cond_resched(); > + } > > return __add_pages(nid, start_pfn, nr_pages, restrictions); > } > @@ -131,13 +138,18 @@ void __ref arch_remove_memory(int nid, u64 start, u64 size, > unsigned long start_pfn = start >> PAGE_SHIFT; > unsigned long nr_pages = size >> PAGE_SHIFT; > struct page *page = pfn_to_page(start_pfn) + vmem_altmap_offset(altmap); > + unsigned long i; > int ret; > > __remove_pages(page_zone(page), start_pfn, nr_pages, altmap); > > /* Remove htab bolted mappings for this section of memory */ > start = (unsigned long)__va(start); > - flush_dcache_range(start, start + size); > + for (i = 0; i < size; i += FLUSH_CHUNK_SIZE) { > + flush_dcache_range(start + i, min(start + size, start + i + FLUSH_CHUNK_SIZE)); > + cond_resched(); > + } > + > ret = remove_section_mapping(start, start + size); > WARN_ON_ONCE(ret); > > Christophe --- L'absence de virus dans ce courrier électronique a été vérifiée par le logiciel antivirus Avast. https://www.avast.com/antivirus
On Thu, 2019-08-15 at 09:36 +0200, christophe leroy wrote: > > Le 15/08/2019 à 06:10, Alastair D'Silva a écrit : > > From: Alastair D'Silva <alastair@d-silva.org> > > > > When presented with large amounts of memory being hotplugged > > (in my test case, ~890GB), the call to flush_dcache_range takes > > a while (~50 seconds), triggering RCU stalls. > > > > This patch breaks up the call into 16GB chunks, calling > > cond_resched() inbetween to allow the scheduler to run. > > Is 16GB small enough ? If 890GB takes 50s, 16GB still takes about 1s. > I'd use 1GB chuncks to remain below 100ms. > > > Signed-off-by: Alastair D'Silva <alastair@d-silva.org> > > --- > > arch/powerpc/mm/mem.c | 16 ++++++++++++++-- > > 1 file changed, 14 insertions(+), 2 deletions(-) > > > > diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c > > index 5400da87a804..fb0d5e9aa11b 100644 > > --- a/arch/powerpc/mm/mem.c > > +++ b/arch/powerpc/mm/mem.c > > @@ -104,11 +104,14 @@ int __weak remove_section_mapping(unsigned > > long start, unsigned long end) > > return -ENODEV; > > } > > > > +#define FLUSH_CHUNK_SIZE (16ull * 1024ull * 1024ull * 1024ull) > > Can we use SZ_16GB ? Sure, I'll go with 1GB as you recommended above > > + > > int __ref arch_add_memory(int nid, u64 start, u64 size, > > struct mhp_restrictions *restrictions) > > { > > unsigned long start_pfn = start >> PAGE_SHIFT; > > unsigned long nr_pages = size >> PAGE_SHIFT; > > + unsigned long i; > > int rc; > > > > resize_hpt_for_hotplug(memblock_phys_mem_size()); > > @@ -120,7 +123,11 @@ int __ref arch_add_memory(int nid, u64 start, > > u64 size, > > start, start + size, rc); > > return -EFAULT; > > } > > - flush_dcache_range(start, start + size); > > + > > + for (i = 0; i < size; i += FLUSH_CHUNK_SIZE) { > > + flush_dcache_range(start + i, min(start + size, start + > > i + FLUSH_CHUNK_SIZE)); > > Isn't the line a bit long (I have not checked). > > > + cond_resched(); > > + } > > > > return __add_pages(nid, start_pfn, nr_pages, restrictions); > > } > > @@ -131,13 +138,18 @@ void __ref arch_remove_memory(int nid, u64 > > start, u64 size, > > unsigned long start_pfn = start >> PAGE_SHIFT; > > unsigned long nr_pages = size >> PAGE_SHIFT; > > struct page *page = pfn_to_page(start_pfn) + > > vmem_altmap_offset(altmap); > > + unsigned long i; > > int ret; > > > > __remove_pages(page_zone(page), start_pfn, nr_pages, altmap); > > > > /* Remove htab bolted mappings for this section of memory */ > > start = (unsigned long)__va(start); > > - flush_dcache_range(start, start + size); > > + for (i = 0; i < size; i += FLUSH_CHUNK_SIZE) { > > + flush_dcache_range(start + i, min(start + size, start + > > i + FLUSH_CHUNK_SIZE)); > > + cond_resched(); > > + } > > + > > ret = remove_section_mapping(start, start + size); > > WARN_ON_ONCE(ret); > > > > > > Christophe > > --- > L'absence de virus dans ce courrier électronique a été vérifiée par > le logiciel antivirus Avast. > https://urldefense.proofpoint.com/v2/url?u=https-3A__www.avast.com_antivirus&d=DwIDaQ&c=jf_iaSHvJObTbx-siA1ZOg&r=cT4tgeEQ0Ll3SIlZDHE5AEXyKy6uKADMtf9_Eb7-vec&m=TBT2NNM2DXqDWHhSb_WdFPcfAjYk9hP2cvGksF001cQ&s=XURKAOQQ4h3_RhJlezSguD2kpSitAF-uBhQqVZLU4GU&e= >
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c index 5400da87a804..fb0d5e9aa11b 100644 --- a/arch/powerpc/mm/mem.c +++ b/arch/powerpc/mm/mem.c @@ -104,11 +104,14 @@ int __weak remove_section_mapping(unsigned long start, unsigned long end) return -ENODEV; } +#define FLUSH_CHUNK_SIZE (16ull * 1024ull * 1024ull * 1024ull) + int __ref arch_add_memory(int nid, u64 start, u64 size, struct mhp_restrictions *restrictions) { unsigned long start_pfn = start >> PAGE_SHIFT; unsigned long nr_pages = size >> PAGE_SHIFT; + unsigned long i; int rc; resize_hpt_for_hotplug(memblock_phys_mem_size()); @@ -120,7 +123,11 @@ int __ref arch_add_memory(int nid, u64 start, u64 size, start, start + size, rc); return -EFAULT; } - flush_dcache_range(start, start + size); + + for (i = 0; i < size; i += FLUSH_CHUNK_SIZE) { + flush_dcache_range(start + i, min(start + size, start + i + FLUSH_CHUNK_SIZE)); + cond_resched(); + } return __add_pages(nid, start_pfn, nr_pages, restrictions); } @@ -131,13 +138,18 @@ void __ref arch_remove_memory(int nid, u64 start, u64 size, unsigned long start_pfn = start >> PAGE_SHIFT; unsigned long nr_pages = size >> PAGE_SHIFT; struct page *page = pfn_to_page(start_pfn) + vmem_altmap_offset(altmap); + unsigned long i; int ret; __remove_pages(page_zone(page), start_pfn, nr_pages, altmap); /* Remove htab bolted mappings for this section of memory */ start = (unsigned long)__va(start); - flush_dcache_range(start, start + size); + for (i = 0; i < size; i += FLUSH_CHUNK_SIZE) { + flush_dcache_range(start + i, min(start + size, start + i + FLUSH_CHUNK_SIZE)); + cond_resched(); + } + ret = remove_section_mapping(start, start + size); WARN_ON_ONCE(ret);