From: "Alastair D'Silva" <alastair@au1.ibm.com>
To: alastair@d-silva.org
Cc: Michal Hocko <mhocko@suse.com>,
David Hildenbrand <david@redhat.com>,
linux-kernel@vger.kernel.org, Nicholas Piggin <npiggin@gmail.com>,
Mike Rapoport <rppt@linux.vnet.ibm.com>, Qian Cai <cai@lca.pw>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Paul Mackerras <paulus@samba.org>,
Thomas Gleixner <tglx@linutronix.de>,
linuxppc-dev@lists.ozlabs.org,
Andrew Morton <akpm@linux-foundation.org>,
Allison Randal <allison@lohutok.net>
Subject: [PATCH v4 5/6] powerpc: Chunk calls to flush_dcache_range in arch_*_memory
Date: Thu, 26 Sep 2019 14:54:11 +1000 [thread overview]
Message-ID: <20190926045419.22827-6-alastair@au1.ibm.com> (raw)
In-Reply-To: <20190926045419.22827-1-alastair@au1.ibm.com>
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 1GB 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 | 27 +++++++++++++++++++++++++--
1 file changed, 25 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index cff947cb2a84..a2758e473d58 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -104,6 +104,27 @@ int __weak remove_section_mapping(unsigned long start, unsigned long end)
return -ENODEV;
}
+#define FLUSH_CHUNK_SIZE SZ_1G
+/**
+ * flush_dcache_range_chunked(): Write any modified data cache blocks out to
+ * memory and invalidate them, in chunks of up to FLUSH_CHUNK_SIZE
+ * Does not invalidate the corresponding instruction cache blocks.
+ *
+ * @start: the start address
+ * @stop: the stop address (exclusive)
+ * @chunk: the max size of the chunks
+ */
+static void flush_dcache_range_chunked(unsigned long start, unsigned long stop,
+ unsigned long chunk)
+{
+ unsigned long i;
+
+ for (i = start; i < stop; i += FLUSH_CHUNK_SIZE) {
+ flush_dcache_range(i, min(stop, start + FLUSH_CHUNK_SIZE));
+ cond_resched();
+ }
+}
+
int __ref arch_add_memory(int nid, u64 start, u64 size,
struct mhp_restrictions *restrictions)
{
@@ -120,7 +141,8 @@ int __ref arch_add_memory(int nid, u64 start, u64 size,
start, start + size, rc);
return -EFAULT;
}
- flush_dcache_range(start, start + size);
+
+ flush_dcache_range_chunked(start, start + size, FLUSH_CHUNK_SIZE);
return __add_pages(nid, start_pfn, nr_pages, restrictions);
}
@@ -137,7 +159,8 @@ void __ref arch_remove_memory(int nid, u64 start, u64 size,
/* Remove htab bolted mappings for this section of memory */
start = (unsigned long)__va(start);
- flush_dcache_range(start, start + size);
+ flush_dcache_range_chunked(start, start + size, FLUSH_CHUNK_SIZE);
+
ret = remove_section_mapping(start, start + size);
WARN_ON_ONCE(ret);
--
2.21.0
next prev parent reply other threads:[~2019-09-26 5:07 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-26 4:54 [PATCH v4 0/6] powerpc: convert cache asm to C Alastair D'Silva
2019-09-26 4:54 ` [PATCH v4 1/6] powerpc: Allow flush_icache_range to work across ranges >4GB Alastair D'Silva
2019-09-26 4:54 ` [PATCH v4 2/6] powerpc: Allow 64bit VDSO __kernel_sync_dicache " Alastair D'Silva
2019-09-26 4:54 ` [PATCH v4 3/6] powerpc: define helpers to get L1 icache sizes Alastair D'Silva
2019-09-26 4:54 ` [PATCH v4 4/6] powerpc: Convert flush_icache_range & friends to C Alastair D'Silva
2019-09-26 4:54 ` Alastair D'Silva [this message]
2019-09-27 6:37 ` [PATCH v4 5/6] powerpc: Chunk calls to flush_dcache_range in arch_*_memory Mark Marshall
2019-09-27 6:46 ` Alastair D'Silva
2019-09-26 4:54 ` [PATCH v4 6/6] powerpc: Don't flush caches when adding memory Alastair D'Silva
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