From: Mathieu Desnoyers Date: Sun, 25 Sep 2016 16:02:25 +0000 (-0400) Subject: Performance: cache the backend pages pointer in context X-Git-Tag: v2.9.0-rc1~10 X-Git-Url: http://git.lttng.org/?p=lttng-modules.git;a=commitdiff_plain;h=85a07c33f3b180d9c1be38832961d0feef66be66 Performance: cache the backend pages pointer in context Getting the backend pages pointer requires pointer chasing through the ring buffer backend tables. Cache the current value so it can be re-used for all backend write operations writing fields for the same event. Signed-off-by: Mathieu Desnoyers --- diff --git a/lib/ringbuffer/backend.h b/lib/ringbuffer/backend.h index b362a04a..9db00956 100644 --- a/lib/ringbuffer/backend.h +++ b/lib/ringbuffer/backend.h @@ -90,26 +90,20 @@ void lib_ring_buffer_write(const struct lib_ring_buffer_config *config, { struct lib_ring_buffer_backend *bufb = &ctx->buf->backend; struct channel_backend *chanb = &ctx->chan->backend; - size_t sbidx, index, pagecpy; + size_t index, pagecpy; size_t offset = ctx->buf_offset; - struct lib_ring_buffer_backend_pages *rpages; - unsigned long sb_bindex, id; + struct lib_ring_buffer_backend_pages *backend_pages; if (unlikely(!len)) return; + backend_pages = + lib_ring_buffer_get_backend_pages_from_ctx(config, ctx); offset &= chanb->buf_size - 1; - sbidx = offset >> chanb->subbuf_size_order; index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT; pagecpy = min_t(size_t, len, (-offset) & ~PAGE_MASK); - id = bufb->buf_wsb[sbidx].id; - sb_bindex = subbuffer_id_get_index(config, id); - rpages = bufb->array[sb_bindex]; - CHAN_WARN_ON(ctx->chan, - config->mode == RING_BUFFER_OVERWRITE - && subbuffer_id_is_noref(config, id)); if (likely(pagecpy == len)) lib_ring_buffer_do_copy(config, - rpages->p[index].virt + backend_pages->p[index].virt + (offset & ~PAGE_MASK), src, len); else @@ -137,25 +131,19 @@ void lib_ring_buffer_memset(const struct lib_ring_buffer_config *config, struct lib_ring_buffer_backend *bufb = &ctx->buf->backend; struct channel_backend *chanb = &ctx->chan->backend; - size_t sbidx, index, pagecpy; + size_t index, pagecpy; size_t offset = ctx->buf_offset; - struct lib_ring_buffer_backend_pages *rpages; - unsigned long sb_bindex, id; + struct lib_ring_buffer_backend_pages *backend_pages; if (unlikely(!len)) return; + backend_pages = + lib_ring_buffer_get_backend_pages_from_ctx(config, ctx); offset &= chanb->buf_size - 1; - sbidx = offset >> chanb->subbuf_size_order; index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT; pagecpy = min_t(size_t, len, (-offset) & ~PAGE_MASK); - id = bufb->buf_wsb[sbidx].id; - sb_bindex = subbuffer_id_get_index(config, id); - rpages = bufb->array[sb_bindex]; - CHAN_WARN_ON(ctx->chan, - config->mode == RING_BUFFER_OVERWRITE - && subbuffer_id_is_noref(config, id)); if (likely(pagecpy == len)) - lib_ring_buffer_do_memset(rpages->p[index].virt + lib_ring_buffer_do_memset(backend_pages->p[index].virt + (offset & ~PAGE_MASK), c, len); else @@ -240,28 +228,22 @@ void lib_ring_buffer_strcpy(const struct lib_ring_buffer_config *config, { struct lib_ring_buffer_backend *bufb = &ctx->buf->backend; struct channel_backend *chanb = &ctx->chan->backend; - size_t sbidx, index, pagecpy; + size_t index, pagecpy; size_t offset = ctx->buf_offset; - struct lib_ring_buffer_backend_pages *rpages; - unsigned long sb_bindex, id; + struct lib_ring_buffer_backend_pages *backend_pages; if (unlikely(!len)) return; + backend_pages = + lib_ring_buffer_get_backend_pages_from_ctx(config, ctx); offset &= chanb->buf_size - 1; - sbidx = offset >> chanb->subbuf_size_order; index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT; pagecpy = min_t(size_t, len, (-offset) & ~PAGE_MASK); - id = bufb->buf_wsb[sbidx].id; - sb_bindex = subbuffer_id_get_index(config, id); - rpages = bufb->array[sb_bindex]; - CHAN_WARN_ON(ctx->chan, - config->mode == RING_BUFFER_OVERWRITE - && subbuffer_id_is_noref(config, id)); if (likely(pagecpy == len)) { size_t count; count = lib_ring_buffer_do_strcpy(config, - rpages->p[index].virt + backend_pages->p[index].virt + (offset & ~PAGE_MASK), src, len - 1); offset += count; @@ -269,13 +251,13 @@ void lib_ring_buffer_strcpy(const struct lib_ring_buffer_config *config, if (unlikely(count < len - 1)) { size_t pad_len = len - 1 - count; - lib_ring_buffer_do_memset(rpages->p[index].virt + lib_ring_buffer_do_memset(backend_pages->p[index].virt + (offset & ~PAGE_MASK), pad, pad_len); offset += pad_len; } /* Ending '\0' */ - lib_ring_buffer_do_memset(rpages->p[index].virt + lib_ring_buffer_do_memset(backend_pages->p[index].virt + (offset & ~PAGE_MASK), '\0', 1); } else { @@ -304,25 +286,19 @@ void lib_ring_buffer_copy_from_user_inatomic(const struct lib_ring_buffer_config { struct lib_ring_buffer_backend *bufb = &ctx->buf->backend; struct channel_backend *chanb = &ctx->chan->backend; - size_t sbidx, index, pagecpy; + size_t index, pagecpy; size_t offset = ctx->buf_offset; - struct lib_ring_buffer_backend_pages *rpages; - unsigned long sb_bindex, id; + struct lib_ring_buffer_backend_pages *backend_pages; unsigned long ret; mm_segment_t old_fs = get_fs(); if (unlikely(!len)) return; + backend_pages = + lib_ring_buffer_get_backend_pages_from_ctx(config, ctx); offset &= chanb->buf_size - 1; - sbidx = offset >> chanb->subbuf_size_order; index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT; pagecpy = min_t(size_t, len, (-offset) & ~PAGE_MASK); - id = bufb->buf_wsb[sbidx].id; - sb_bindex = subbuffer_id_get_index(config, id); - rpages = bufb->array[sb_bindex]; - CHAN_WARN_ON(ctx->chan, - config->mode == RING_BUFFER_OVERWRITE - && subbuffer_id_is_noref(config, id)); set_fs(KERNEL_DS); pagefault_disable(); @@ -331,7 +307,7 @@ void lib_ring_buffer_copy_from_user_inatomic(const struct lib_ring_buffer_config if (likely(pagecpy == len)) { ret = lib_ring_buffer_do_copy_from_user_inatomic( - rpages->p[index].virt + (offset & ~PAGE_MASK), + backend_pages->p[index].virt + (offset & ~PAGE_MASK), src, len); if (unlikely(ret > 0)) { /* Copy failed. */ @@ -381,24 +357,18 @@ void lib_ring_buffer_strcpy_from_user_inatomic(const struct lib_ring_buffer_conf { struct lib_ring_buffer_backend *bufb = &ctx->buf->backend; struct channel_backend *chanb = &ctx->chan->backend; - size_t sbidx, index, pagecpy; + size_t index, pagecpy; size_t offset = ctx->buf_offset; - struct lib_ring_buffer_backend_pages *rpages; - unsigned long sb_bindex, id; + struct lib_ring_buffer_backend_pages *backend_pages; mm_segment_t old_fs = get_fs(); if (unlikely(!len)) return; + backend_pages = + lib_ring_buffer_get_backend_pages_from_ctx(config, ctx); offset &= chanb->buf_size - 1; - sbidx = offset >> chanb->subbuf_size_order; index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT; pagecpy = min_t(size_t, len, (-offset) & ~PAGE_MASK); - id = bufb->buf_wsb[sbidx].id; - sb_bindex = subbuffer_id_get_index(config, id); - rpages = bufb->array[sb_bindex]; - CHAN_WARN_ON(ctx->chan, - config->mode == RING_BUFFER_OVERWRITE - && subbuffer_id_is_noref(config, id)); set_fs(KERNEL_DS); pagefault_disable(); @@ -409,7 +379,7 @@ void lib_ring_buffer_strcpy_from_user_inatomic(const struct lib_ring_buffer_conf size_t count; count = lib_ring_buffer_do_strcpy_from_user_inatomic(config, - rpages->p[index].virt + backend_pages->p[index].virt + (offset & ~PAGE_MASK), src, len - 1); offset += count; @@ -417,13 +387,13 @@ void lib_ring_buffer_strcpy_from_user_inatomic(const struct lib_ring_buffer_conf if (unlikely(count < len - 1)) { size_t pad_len = len - 1 - count; - lib_ring_buffer_do_memset(rpages->p[index].virt + lib_ring_buffer_do_memset(backend_pages->p[index].virt + (offset & ~PAGE_MASK), pad, pad_len); offset += pad_len; } /* Ending '\0' */ - lib_ring_buffer_do_memset(rpages->p[index].virt + lib_ring_buffer_do_memset(backend_pages->p[index].virt + (offset & ~PAGE_MASK), '\0', 1); } else { diff --git a/lib/ringbuffer/backend_internal.h b/lib/ringbuffer/backend_internal.h index fc5bec53..e03d8c0b 100644 --- a/lib/ringbuffer/backend_internal.h +++ b/lib/ringbuffer/backend_internal.h @@ -201,6 +201,37 @@ int subbuffer_id_check_index(const struct lib_ring_buffer_config *config, return 0; } +static inline +void lib_ring_buffer_backend_get_pages(const struct lib_ring_buffer_config *config, + struct lib_ring_buffer_ctx *ctx, + struct lib_ring_buffer_backend_pages **backend_pages) +{ + struct lib_ring_buffer_backend *bufb = &ctx->buf->backend; + struct channel_backend *chanb = &ctx->chan->backend; + size_t sbidx, offset = ctx->buf_offset; + unsigned long sb_bindex, id; + struct lib_ring_buffer_backend_pages *rpages; + + offset &= chanb->buf_size - 1; + sbidx = offset >> chanb->subbuf_size_order; + id = bufb->buf_wsb[sbidx].id; + sb_bindex = subbuffer_id_get_index(config, id); + rpages = bufb->array[sb_bindex]; + CHAN_WARN_ON(ctx->chan, + config->mode == RING_BUFFER_OVERWRITE + && subbuffer_id_is_noref(config, id)); + *backend_pages = rpages; +} + +/* Get backend pages from cache. */ +static inline +struct lib_ring_buffer_backend_pages * + lib_ring_buffer_get_backend_pages_from_ctx(const struct lib_ring_buffer_config *config, + struct lib_ring_buffer_ctx *ctx) +{ + return ctx->backend_pages; +} + /* * The ring buffer can count events recorded and overwritten per buffer, * but it is disabled by default due to its performance overhead. diff --git a/lib/ringbuffer/config.h b/lib/ringbuffer/config.h index 63189b95..60174db6 100644 --- a/lib/ringbuffer/config.h +++ b/lib/ringbuffer/config.h @@ -200,6 +200,8 @@ struct lib_ring_buffer_ctx { */ u64 tsc; /* time-stamp counter value */ unsigned int rflags; /* reservation flags */ + /* Cache backend pages pointer chasing. */ + struct lib_ring_buffer_backend_pages *backend_pages; }; /** @@ -223,6 +225,7 @@ void lib_ring_buffer_ctx_init(struct lib_ring_buffer_ctx *ctx, ctx->largest_align = largest_align; ctx->cpu = cpu; ctx->rflags = 0; + ctx->backend_pages = NULL; } /* diff --git a/lttng-ring-buffer-client.h b/lttng-ring-buffer-client.h index 7c9ae443..c4b7304f 100644 --- a/lttng-ring-buffer-client.h +++ b/lttng-ring-buffer-client.h @@ -626,6 +626,8 @@ int lttng_event_reserve(struct lib_ring_buffer_ctx *ctx, ret = lib_ring_buffer_reserve(&client_config, ctx); if (ret) goto put; + lib_ring_buffer_backend_get_pages(&client_config, ctx, + &ctx->backend_pages); lttng_write_event_header(&client_config, ctx, event_id); return 0; put: diff --git a/lttng-ring-buffer-metadata-client.h b/lttng-ring-buffer-metadata-client.h index c441372e..b2c0c821 100644 --- a/lttng-ring-buffer-metadata-client.h +++ b/lttng-ring-buffer-metadata-client.h @@ -312,7 +312,15 @@ void lttng_buffer_read_close(struct lib_ring_buffer *buf) static int lttng_event_reserve(struct lib_ring_buffer_ctx *ctx, uint32_t event_id) { - return lib_ring_buffer_reserve(&client_config, ctx); + int ret; + + ret = lib_ring_buffer_reserve(&client_config, ctx); + if (ret) + return ret; + lib_ring_buffer_backend_get_pages(&client_config, ctx, + &ctx->backend_pages); + return 0; + } static