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Date: Wed, 6 Sep 2006 07:50:31 -0700 From: Stephane Eranian <eranian@....hp.com> To: Andrew Morton <akpm@...l.org> Cc: linux-kernel@...r.kernel.org Subject: Re: [PATCH 8/18] 2.6.17.9 perfmon2 patch for review: event sets and multiplexing support Andrew, On Wed, Aug 23, 2006 at 03:51:48PM -0700, Andrew Morton wrote: > > > > +struct pfm_event_set *pfm_find_set(struct pfm_context *ctx, u16 set_id, > > + int alloc) > > +{ > > + kmem_cache_t *cachep; > > + struct pfm_event_set *set, *new_set, *prev; > > + unsigned long offs; > > + size_t view_size; > > + void *view; > > + > > + PFM_DBG("looking for set=%u", set_id); > > + > > + /* > > + * shortcut for set 0: always exist, cannot be removed > > + */ > > + if (set_id == 0 && !alloc) > > + return list_entry(ctx->list.next, struct pfm_event_set, list); > > + > > + prev = NULL; > > + list_for_each_entry(set, &ctx->list, list) { > > + if (set->id == set_id) > > + return set; > > + if (set->id > set_id) > > + break; > > + prev = set; > > + } > > + > > + if (!alloc) > > + return NULL; > > + > > + cachep = ctx->flags.mapset ? pfm_set_cachep : pfm_lg_set_cachep; > > + > > + new_set = kmem_cache_alloc(cachep, SLAB_ATOMIC); > > SLAB_ATOMIC is unreliable. Is it possible to use SLAB_KERNEL here? If > coms ecallers can sleep and others cannot then passing in the gfp_flags > would permit improvement here. > I made some changes and now I know I execute this part of the function with interrupts disabled, holding only the perfmon context lock. I assume SLAB_KERNEL means, we can sleep. I think I can make this change safely. > > > + if (ctx->flags.mapset) { > > + view_size = PAGE_ALIGN(sizeof(struct pfm_set_view)); > > + view = vmalloc(view_size); > > vmalloc() sleeps, so this _could_ have used SLAB_ATOMIC. > I am not sure I follow you here. Are you talking about eh kmem_cache_alloc() above? > > +static struct page *pfm_view_map_pagefault(struct vm_area_struct *vma, > > + unsigned long address, int *type) > > +{ > > + void *kaddr; > > + struct page *page; > > + > > + kaddr = vma->vm_private_data; > > + if (kaddr == NULL) { > > + PFM_DBG("no view"); > > + return NOPAGE_SIGBUS; > > + } > > + > > + if ( (address < (unsigned long) vma->vm_start) || > > + (address > (unsigned long) (vma->vm_start + PAGE_SIZE)) ) > > Should that be >=? Yes. Thanks. -- -Stephane - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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