On 05/02/2011 14:07, "Olaf Hering" <olaf@xxxxxxxxx> wrote:
>
> Allocate tracebuffers dynamically, based on the requested buffer size.
> Calculate t_info_size from requested t_buf size.
> Fix allocation failure path, free pages without the spinlock.
> The spinlock is not needed since tracing is not yet enabled.
> Remove casts for rawbuf, it can be a void pointer since no math is done.
Bit big for 4.1 now I think. Needs an Ack from George Dunlap also.
-- Keir
> Signed-off-by: Olaf Hering <olaf@xxxxxxxxx>
>
> ---
> xen/common/trace.c | 214
> ++++++++++++++++++++++-------------------------------
> 1 file changed, 91 insertions(+), 123 deletions(-)
>
> --- xen-unstable.hg-4.1.22870.orig/xen/common/trace.c
> +++ xen-unstable.hg-4.1.22870/xen/common/trace.c
> @@ -42,14 +42,14 @@ CHECK_t_buf;
> #define compat_t_rec t_rec
> #endif
>
> -/* opt_tbuf_size: trace buffer size (in pages) */
> -static unsigned int opt_tbuf_size = 0;
> +/* opt_tbuf_size: trace buffer size (in pages) for each cpu */
> +static unsigned int opt_tbuf_size;
> integer_param("tbuf_size", opt_tbuf_size);
>
> /* Pointers to the meta-data objects for all system trace buffers */
> static struct t_info *t_info;
> -#define T_INFO_PAGES 2 /* Size fixed at 2 pages for now. */
> -#define T_INFO_SIZE ((T_INFO_PAGES)*(PAGE_SIZE))
> +static unsigned int t_info_pages;
> +
> static DEFINE_PER_CPU_READ_MOSTLY(struct t_buf *, t_bufs);
> static DEFINE_PER_CPU_READ_MOSTLY(unsigned char *, t_data);
> static DEFINE_PER_CPU_READ_MOSTLY(spinlock_t, t_lock);
> @@ -78,6 +78,21 @@ static u32 tb_event_mask = TRC_ALL;
> * i.e., sizeof(_type) * ans >= _x. */
> #define fit_to_type(_type, _x) (((_x)+sizeof(_type)-1) / sizeof(_type))
>
> +static int cpu_callback(
> + struct notifier_block *nfb, unsigned long action, void *hcpu)
> +{
> + unsigned int cpu = (unsigned long)hcpu;
> +
> + if ( action == CPU_UP_PREPARE )
> + spin_lock_init(&per_cpu(t_lock, cpu));
> +
> + return NOTIFY_DONE;
> +}
> +
> +static struct notifier_block cpu_nfb = {
> + .notifier_call = cpu_callback
> +};
> +
> static void calc_tinfo_first_offset(void)
> {
> int offset_in_bytes = offsetof(struct t_info, mfn_offset[NR_CPUS]);
> @@ -85,20 +100,30 @@ static void calc_tinfo_first_offset(void
> }
>
> /**
> - * check_tbuf_size - check to make sure that the proposed size will fit
> + * calculate_tbuf_size - check to make sure that the proposed size will fit
> * in the currently sized struct t_info and allows prod and cons to
> * reach double the value without overflow.
> */
> -static int check_tbuf_size(u32 pages)
> +static int calculate_tbuf_size(unsigned int pages)
> {
> struct t_buf dummy;
> - typeof(dummy.prod) size;
> -
> - size = ((typeof(dummy.prod))pages) * PAGE_SIZE;
> -
> - return (size / PAGE_SIZE != pages)
> - || (size + size < size)
> - || (num_online_cpus() * pages + t_info_first_offset > T_INFO_SIZE
> / sizeof(uint32_t));
> + typeof(dummy.prod) size = -1;
> +
> + /* max size holds up to n pages */
> + size /= PAGE_SIZE;
> + if ( pages > size )
> + {
> + gdprintk(XENLOG_INFO, "%s: requested number of %u pages reduced to
> %u\n",
> + __func__, pages, (unsigned int)size);
> + pages = size;
> + }
> +
> + t_info_pages = num_online_cpus() * pages + t_info_first_offset;
> + t_info_pages *= sizeof(uint32_t);
> + t_info_pages /= PAGE_SIZE;
> + if ( t_info_pages % PAGE_SIZE )
> + t_info_pages++;
> + return pages;
> }
>
> /**
> @@ -111,47 +136,48 @@ static int check_tbuf_size(u32 pages)
> * This function may also be called later when enabling trace buffers
> * via the SET_SIZE hypercall.
> */
> -static int alloc_trace_bufs(void)
> +static int alloc_trace_bufs(unsigned int pages)
> {
> - int i, cpu, order;
> - unsigned long nr_pages;
> + int i, cpu, order;
> /* Start after a fixed-size array of NR_CPUS */
> uint32_t *t_info_mfn_list;
> int offset;
>
> - if ( opt_tbuf_size == 0 )
> - return -EINVAL;
> -
> - if ( check_tbuf_size(opt_tbuf_size) )
> + if ( t_info )
> {
> - printk("Xen trace buffers: tb size %d too large. "
> - "Tracing disabled.\n",
> - opt_tbuf_size);
> - return -EINVAL;
> + printk("Xen trace buffers: t_info already allocated.\n");
> + return -EBUSY;
> }
>
> - /* t_info size is fixed for now. Currently this works great, so there
> - * seems to be no need to make it dynamic. */
> - t_info = alloc_xenheap_pages(get_order_from_pages(T_INFO_PAGES), 0);
> + if ( pages == 0 )
> + return -EINVAL;
> +
> + /* Calculate offset in u32 of first mfn */
> + calc_tinfo_first_offset();
> +
> + pages = calculate_tbuf_size(pages);
> + order = get_order_from_pages(pages);
> +
> + t_info = alloc_xenheap_pages(get_order_from_pages(t_info_pages), 0);
> if ( t_info == NULL )
> {
> - printk("Xen trace buffers: t_info allocation failed! "
> - "Tracing disabled.\n");
> + printk("Xen trace buffers: t_info allocation failed! Tracing
> disabled.\n");
> return -ENOMEM;
> }
>
> - for ( i = 0; i < T_INFO_PAGES; i++ )
> - share_xen_page_with_privileged_guests(
> - virt_to_page(t_info) + i, XENSHARE_readonly);
> -
> - t_info_mfn_list = (uint32_t *)t_info;
> offset = t_info_first_offset;
> + t_info_mfn_list = (uint32_t *)t_info;
>
> - t_info->tbuf_size = opt_tbuf_size;
> - printk(XENLOG_INFO "tbuf_size %d\n", t_info->tbuf_size);
> + /* Per-cpu t_lock initialisation. */
> + for_each_online_cpu ( cpu )
> + spin_lock_init(&per_cpu(t_lock, cpu));
> + register_cpu_notifier(&cpu_nfb);
>
> - nr_pages = opt_tbuf_size;
> - order = get_order_from_pages(nr_pages);
> + for(i = 0; i < t_info_pages; i++)
> + share_xen_page_with_privileged_guests(
> + virt_to_page(t_info) + i, XENSHARE_readonly);
> +
> + t_info->tbuf_size = pages;
>
> /*
> * First, allocate buffers for all of the cpus. If any
> @@ -160,25 +186,19 @@ static int alloc_trace_bufs(void)
> for_each_online_cpu(cpu)
> {
> int flags;
> - char *rawbuf;
> + void *rawbuf;
> struct t_buf *buf;
>
> if ( (rawbuf = alloc_xenheap_pages(
> order, MEMF_bits(32 + PAGE_SHIFT))) == NULL )
> {
> - printk("Xen trace buffers: memory allocation failed\n");
> - opt_tbuf_size = 0;
> + printk("Xen trace buffers: memory allocation failed on cpu %d\n",
> cpu);
> goto out_dealloc;
> }
>
> - spin_lock_irqsave(&per_cpu(t_lock, cpu), flags);
> -
> - per_cpu(t_bufs, cpu) = buf = (struct t_buf *)rawbuf;
> + per_cpu(t_bufs, cpu) = buf = rawbuf;
> buf->cons = buf->prod = 0;
> per_cpu(t_data, cpu) = (unsigned char *)(buf + 1);
> -
> - spin_unlock_irqrestore(&per_cpu(t_lock, cpu), flags);
> -
> }
>
> /*
> @@ -188,14 +208,14 @@ static int alloc_trace_bufs(void)
> for_each_online_cpu(cpu)
> {
> /* Share pages so that xentrace can map them. */
> - char *rawbuf;
> + void *rawbuf;
>
> - if ( (rawbuf = (char *)per_cpu(t_bufs, cpu)) )
> + if ( (rawbuf = per_cpu(t_bufs, cpu)) )
> {
> struct page_info *p = virt_to_page(rawbuf);
> uint32_t mfn = virt_to_mfn(rawbuf);
>
> - for ( i = 0; i < nr_pages; i++ )
> + for ( i = 0; i < pages; i++ )
> {
> share_xen_page_with_privileged_guests(
> p + i, XENSHARE_writable);
> @@ -211,24 +231,28 @@ static int alloc_trace_bufs(void)
> }
> }
>
> - data_size = (opt_tbuf_size * PAGE_SIZE - sizeof(struct t_buf));
> + data_size = (pages * PAGE_SIZE - sizeof(struct t_buf));
> t_buf_highwater = data_size >> 1; /* 50% high water */
> + opt_tbuf_size = pages;
> +
> + printk("Xen trace buffers: initialised\n");
> + wmb(); /* above must be visible before tb_init_done flag set */
> + tb_init_done = 1;
>
> return 0;
> out_dealloc:
> for_each_online_cpu(cpu)
> {
> int flags;
> - char * rawbuf;
> + void *rawbuf;
>
> - spin_lock_irqsave(&per_cpu(t_lock, cpu), flags);
> - if ( (rawbuf = (char *)per_cpu(t_bufs, cpu)) )
> + rawbuf = per_cpu(t_bufs, cpu);
> + per_cpu(t_bufs, cpu) = NULL;
> + if ( rawbuf )
> {
> - per_cpu(t_bufs, cpu) = NULL;
> ASSERT(!(virt_to_page(rawbuf)->count_info & PGC_allocated));
> free_xenheap_pages(rawbuf, order);
> }
> - spin_unlock_irqrestore(&per_cpu(t_lock, cpu), flags);
> }
>
> return -ENOMEM;
> @@ -236,41 +260,25 @@ out_dealloc:
>
>
> /**
> - * tb_set_size - handle the logic involved with dynamically
> - * allocating and deallocating tbufs
> + * tb_set_size - handle the logic involved with dynamically allocating tbufs
> *
> * This function is called when the SET_SIZE hypercall is done.
> */
> -static int tb_set_size(int size)
> +static int tb_set_size(unsigned int pages)
> {
> /*
> * Setting size is a one-shot operation. It can be done either at
> * boot time or via control tools, but not by both. Once buffers
> * are created they cannot be destroyed.
> */
> - int ret = 0;
> -
> - if ( opt_tbuf_size != 0 )
> + if ( opt_tbuf_size && pages != opt_tbuf_size )
> {
> - if ( size != opt_tbuf_size )
> - gdprintk(XENLOG_INFO, "tb_set_size from %d to %d not
> implemented\n",
> - opt_tbuf_size, size);
> + gdprintk(XENLOG_INFO, "tb_set_size from %d to %d not implemented\n",
> + opt_tbuf_size, pages);
> return -EINVAL;
> }
>
> - if ( size <= 0 )
> - return -EINVAL;
> -
> - opt_tbuf_size = size;
> -
> - if ( (ret = alloc_trace_bufs()) != 0 )
> - {
> - opt_tbuf_size = 0;
> - return ret;
> - }
> -
> - printk("Xen trace buffers: initialized\n");
> - return 0;
> + return alloc_trace_bufs(pages);
> }
>
> int trace_will_trace_event(u32 event)
> @@ -299,21 +307,6 @@ int trace_will_trace_event(u32 event)
> return 1;
> }
>
> -static int cpu_callback(
> - struct notifier_block *nfb, unsigned long action, void *hcpu)
> -{
> - unsigned int cpu = (unsigned long)hcpu;
> -
> - if ( action == CPU_UP_PREPARE )
> - spin_lock_init(&per_cpu(t_lock, cpu));
> -
> - return NOTIFY_DONE;
> -}
> -
> -static struct notifier_block cpu_nfb = {
> - .notifier_call = cpu_callback
> -};
> -
> /**
> * init_trace_bufs - performs initialization of the per-cpu trace buffers.
> *
> @@ -323,37 +316,12 @@ static struct notifier_block cpu_nfb = {
> */
> void __init init_trace_bufs(void)
> {
> - int i;
> -
> - /* Calculate offset in u32 of first mfn */
> - calc_tinfo_first_offset();
> -
> - /* Per-cpu t_lock initialisation. */
> - for_each_online_cpu ( i )
> - spin_lock_init(&per_cpu(t_lock, i));
> - register_cpu_notifier(&cpu_nfb);
> -
> - if ( opt_tbuf_size == 0 )
> - {
> - printk("Xen trace buffers: disabled\n");
> - goto fail;
> - }
> -
> - if ( alloc_trace_bufs() != 0 )
> + if ( opt_tbuf_size && alloc_trace_bufs(opt_tbuf_size) )
> {
> - dprintk(XENLOG_INFO, "Xen trace buffers: "
> - "allocation size %d failed, disabling\n",
> - opt_tbuf_size);
> - goto fail;
> + gdprintk(XENLOG_INFO, "Xen trace buffers: "
> + "allocation size %d failed, disabling\n",
> + opt_tbuf_size);
> }
> -
> - printk("Xen trace buffers: initialised\n");
> - wmb(); /* above must be visible before tb_init_done flag set */
> - tb_init_done = 1;
> - return;
> -
> - fail:
> - opt_tbuf_size = 0;
> }
>
> /**
> @@ -372,7 +340,7 @@ int tb_control(xen_sysctl_tbuf_op_t *tbc
> case XEN_SYSCTL_TBUFOP_get_info:
> tbc->evt_mask = tb_event_mask;
> tbc->buffer_mfn = t_info ? virt_to_mfn(t_info) : 0;
> - tbc->size = T_INFO_PAGES * PAGE_SIZE;
> + tbc->size = t_info_pages * PAGE_SIZE;
> break;
> case XEN_SYSCTL_TBUFOP_set_cpu_mask:
> rc = xenctl_cpumap_to_cpumask(&tb_cpu_mask, &tbc->cpu_mask);
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-devel
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