From mboxrd@z Thu Jan 1 00:00:00 1970 From: Xiao Guangrong Subject: Re: [PATCH v3 2/5] util: introduce threaded workqueue Date: Mon, 26 Nov 2018 15:57:25 +0800 Message-ID: References: <20181122072028.22819-1-xiaoguangrong@tencent.com> <20181122072028.22819-3-xiaoguangrong@tencent.com> <20181123110239.GC2373@work-vm> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Cc: kvm@vger.kernel.org, mst@redhat.com, mtosatti@redhat.com, Xiao Guangrong , qemu-devel@nongnu.org, peterx@redhat.com, quintela@redhat.com, wei.w.wang@intel.com, cota@braap.org, jiang.biao2@zte.com.cn, pbonzini@redhat.com To: "Dr. David Alan Gilbert" Return-path: In-Reply-To: <20181123110239.GC2373@work-vm> Content-Language: en-US List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+gceq-qemu-devel2=m.gmane.org@nongnu.org Sender: "Qemu-devel" List-Id: kvm.vger.kernel.org On 11/23/18 7:02 PM, Dr. David Alan Gilbert wrote: >> +#include "qemu/osdep.h" >> +#include "qemu/bitmap.h" >> +#include "qemu/threaded-workqueue.h" >> + >> +#define SMP_CACHE_BYTES 64 > > That's architecture dependent isn't it? > Yes, it's arch dependent indeed. I just used 64 for simplification and i think it is <= 64 on most CPU arch-es so that can work. Should i introduce statically defined CACHE LINE SIZE for all arch-es? :( >> + /* >> + * the bit in these two bitmaps indicates the index of the ï¼ requests >> + * respectively. If it's the same, the corresponding request is free >> + * and owned by the user, i.e, where the user fills a request. Otherwise, >> + * it is valid and owned by the thread, i.e, where the thread fetches >> + * the request and write the result. >> + */ >> + >> + /* after the user fills the request, the bit is flipped. */ >> + uint64_t request_fill_bitmap QEMU_ALIGNED(SMP_CACHE_BYTES); >> + /* after handles the request, the thread flips the bit. */ >> + uint64_t request_done_bitmap QEMU_ALIGNED(SMP_CACHE_BYTES); > > Patchew complained about some type mismatches; I think those are because > you're using the bitmap_* functions on these; those functions always > operate on 'long' not on uint64_t - and on some platforms they're > unfortunately not the same. I guess you were taking about this error: ERROR: externs should be avoided in .c files #233: FILE: util/threaded-workqueue.c:65: + uint64_t request_fill_bitmap QEMU_ALIGNED(SMP_CACHE_BYTES); The complained thing is "QEMU_ALIGNED(SMP_CACHE_BYTES)" as it gone when the aligned thing is removed... The issue you pointed out can be avoid by using type-casting, like: bitmap_xor(..., (void *)&thread->request_fill_bitmap) cannot we? Thanks!