Re: Perfomance degradation 9.3 (vs 9.2) for FreeBSD

Hello,

How did this testing turn out?

Palle

3 jul 2014 kl. 12:15 skrev Tatsuo Ishii <ishii(at)postgresql(dot)org>:

> Hi,
>
>> Hi,
>>
>> Attached you can find a short (compile tested only ) patch implementing
>> a 'shared_memory_type' GUC, akin to 'dynamic_shared_memory_type'. Will
>> only apply to 9.4, not 9.3, but it should be easy to convert for it.
>>
>> Greetings,
>>
>> Andres Freund
>
> I have rebased Andres's patch against 9.3-STABLE tree. Please take a
> look at attached patches and let me know if you find anything strange.
>
> I am going to test the patch on a huge HP machine: DL980G7/64
> cores/2TB mem. With the patch I would be able to report back if using
> SysV shared mem fixes the 9.3 performance problem.
>
> Best regards,
> --
> Tatsuo Ishii
> SRA OSS, Inc. Japan
> English: http://www.sraoss.co.jp/index_en.php
> Japanese:http://www.sraoss.co.jp
> diff --git a/src/backend/port/sysv_shmem.c b/src/backend/port/sysv_shmem.c
> index f746c81..e82054a 100644
> --- a/src/backend/port/sysv_shmem.c
> +++ b/src/backend/port/sysv_shmem.c
> @@ -72,6 +72,7 @@ static void IpcMemoryDetach(int status, Datum shmaddr);
> static void IpcMemoryDelete(int status, Datum shmId);
> static PGShmemHeader *PGSharedMemoryAttach(IpcMemoryKey key,
> IpcMemoryId *shmid);
> +static void *CreateAnonymousSegment(Size *size);
>
>
> /*
> @@ -389,49 +390,19 @@ PGSharedMemoryCreate(Size size, bool makePrivate, int port)
> * developer use, this shouldn't be a big problem.
> */
> #ifndef EXEC_BACKEND
> + if (shared_memory_type == SHMEM_TYPE_MMAP)
> {
> - long pagesize = sysconf(_SC_PAGE_SIZE);
> -
> - /*
> - * Ensure request size is a multiple of pagesize.
> - *
> - * pagesize will, for practical purposes, always be a power of two.
> - * But just in case it isn't, we do it this way instead of using
> - * TYPEALIGN().
> - */
> - if (pagesize > 0 && size % pagesize != 0)
> - size += pagesize - (size % pagesize);
> -
> - /*
> - * We assume that no one will attempt to run PostgreSQL 9.3 or later
> - * on systems that are ancient enough that anonymous shared memory is
> - * not supported, such as pre-2.4 versions of Linux. If that turns
> - * out to be false, we might need to add a run-time test here and do
> - * this only if the running kernel supports it.
> - */
> - AnonymousShmem = mmap(NULL, size, PROT_READ | PROT_WRITE, PG_MMAP_FLAGS,
> - -1, 0);
> - if (AnonymousShmem == MAP_FAILED)
> - {
> - int saved_errno = errno;
> -
> - ereport(FATAL,
> - (errmsg("could not map anonymous shared memory: %m"),
> - (saved_errno == ENOMEM) ?
> - errhint("This error usually means that PostgreSQL's request "
> - "for a shared memory segment exceeded available memory "
> - "or swap space. To reduce the request size (currently "
> - "%lu bytes), reduce PostgreSQL's shared memory usage, "
> - "perhaps by reducing shared_buffers or "
> - "max_connections.",
> - (unsigned long) size) : 0));
> - }
> + AnonymousShmem = CreateAnonymousSegment(&size);
> AnonymousShmemSize = size;
> -
> /* Now we need only allocate a minimal-sized SysV shmem block. */
> sysvsize = sizeof(PGShmemHeader);
> }
> + else
> #endif
> + {
> + Assert(shared_memory_type == SHMEM_TYPE_SYSV);
> + sysvsize = size;
> + }
>
> /* Make sure PGSharedMemoryAttach doesn't fail without need */
> UsedShmemSegAddr = NULL;
> @@ -631,3 +602,47 @@ PGSharedMemoryAttach(IpcMemoryKey key, IpcMemoryId *shmid)
>
> return hdr;
> }
> +
> +/*
> + * Creates an anonymous mmap()ed shared memory segment.
> + *
> + * Pass the requested size in *size. This function will modify *size to the
> + * actual size of the allocation, if it ends up allocating a segment that is
> + * larger than requested.
> + */
> +#ifndef EXEC_BACKEND
> +static void *
> +CreateAnonymousSegment(Size *size)
> +{
> + Size allocsize = *size;
> + void *ptr = MAP_FAILED;
> + int mmap_errno = 0;
> +
> + /*
> + * use the original size, not the rounded up value, when falling back
> + * to non-huge pages.
> + */
> + allocsize = *size;
> + ptr = mmap(NULL, allocsize, PROT_READ | PROT_WRITE,
> + PG_MMAP_FLAGS, -1, 0);
> + mmap_errno = errno;
> +
> + if (ptr == MAP_FAILED)
> + {
> + errno = mmap_errno;
> + ereport(FATAL,
> + (errmsg("could not map anonymous shared memory: %m"),
> + (mmap_errno == ENOMEM) ?
> + errhint("This error usually means that PostgreSQL's request "
> + "for a shared memory segment exceeded available memory, "
> + "swap space or huge pages. To reduce the request size "
> + "(currently %zu bytes), reduce PostgreSQL's shared "
> + "memory usage, perhaps by reducing shared_buffers or "
> + "max_connections.",
> + *size) : 0));
> + }
> +
> + *size = allocsize;
> + return ptr;
> +}
> +#endif
> diff --git a/src/backend/storage/ipc/ipci.c b/src/backend/storage/ipc/ipci.c
> index 918ac51..51dccdc 100644
> --- a/src/backend/storage/ipc/ipci.c
> +++ b/src/backend/storage/ipc/ipci.c
> @@ -39,6 +39,8 @@
> #include "storage/sinvaladt.h"
> #include "storage/spin.h"
>
> +/* GUCs */
> +int shared_memory_type = DEFAULT_SHARED_MEMORY_TYPE;
>
> shmem_startup_hook_type shmem_startup_hook = NULL;
>
> diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
> index 2b6527f..2945a68 100644
> --- a/src/backend/utils/misc/guc.c
> +++ b/src/backend/utils/misc/guc.c
> @@ -61,6 +61,7 @@
> #include "replication/walreceiver.h"
> #include "replication/walsender.h"
> #include "storage/bufmgr.h"
> +#include "storage/pg_shmem.h"
> #include "storage/standby.h"
> #include "storage/fd.h"
> #include "storage/proc.h"
> @@ -378,6 +379,19 @@ static const struct config_enum_entry synchronous_commit_options[] = {
> {NULL, 0, false}
> };
>
> +static struct config_enum_entry shared_memory_options[] = {
> +#ifndef WIN32
> + { "sysv", SHMEM_TYPE_SYSV, false},
> +#endif
> +#ifndef EXEC_BACKEND
> + { "mmap", SHMEM_TYPE_MMAP, false},
> +#endif
> +#ifdef WIN32
> + { "windows", SHMEM_TYPE_WINDOWS, false},
> +#endif
> + {NULL, 0, false}
> +};
> +
> /*
> * Options for enum values stored in other modules
> */
> @@ -3328,6 +3342,16 @@ static struct config_enum ConfigureNamesEnum[] =
> },
>
> {
> + {"shared_memory_type", PGC_POSTMASTER, RESOURCES_MEM,
> + gettext_noop("Selects the shared memory implementation used."),
> + NULL
> + },
> + &shared_memory_type,
> + DEFAULT_SHARED_MEMORY_TYPE, shared_memory_options,
> + NULL, NULL, NULL
> + },
> +
> + {
> {"wal_sync_method", PGC_SIGHUP, WAL_SETTINGS,
> gettext_noop("Selects the method used for forcing WAL updates to disk."),
> NULL
> diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
> index 18196f8..022cf4d 100644
> --- a/src/backend/utils/misc/postgresql.conf.sample
> +++ b/src/backend/utils/misc/postgresql.conf.sample
> @@ -124,6 +124,13 @@
> #maintenance_work_mem = 16MB # min 1MB
> #max_stack_depth = 2MB # min 100kB
>
> +#shared_memory_type = mmap # the default is the first option
> + # supported by the operating system:
> + # mmap
> + # sysv
> + # windows
> +#dynamic_shared_memory_type = posix # the default is the first option
> +
> # - Disk -
>
> #temp_file_limit = -1 # limits per-session temp file space
> diff --git a/src/include/storage/pg_shmem.h b/src/include/storage/pg_shmem.h
> index 6ece82b..9c3b6d9 100644
> --- a/src/include/storage/pg_shmem.h
> +++ b/src/include/storage/pg_shmem.h
> @@ -38,6 +38,27 @@ typedef struct PGShmemHeader /* standard header for all Postgres shmem */
> #endif
> } PGShmemHeader;
>
> +/* GUC variable */
> +extern int huge_pages;
> +/* Possible values for shared_memory_type */
> +typedef enum
> +{
> + SHMEM_TYPE_WINDOWS,
> + SHMEM_TYPE_SYSV,
> + SHMEM_TYPE_MMAP
> +} PGShmemType;
> +
> +#if !defined(WIN32) && !defined(EXEC_BACKEND)
> +#define DEFAULT_SHARED_MEMORY_TYPE SHMEM_TYPE_MMAP
> +#elif !defined(WIN32)
> +#define DEFAULT_SHARED_MEMORY_TYPE SHMEM_TYPE_SYSV
> +#else
> +#define DEFAULT_SHARED_MEMORY_TYPE SHMEM_TYPE_WINDOWS
> +#endif
> +
> +/* GUC variables */
> +extern int shared_memory_type;
> +extern int huge_pages;
>
> #ifdef EXEC_BACKEND
> #ifndef WIN32