On 16/09/2014 02:08, Ma, Jianpeng wrote: >> -----Original Message----- >> From: Sage Weil [mailto:sweil@xxxxxxxxxx] >> Sent: Tuesday, September 16, 2014 8:02 AM >> To: Ma, Jianpeng >> Cc: Loic Dachary; Janne Grunau; ceph-devel@xxxxxxxxxxxxxxx >> Subject: RE: [PATCH 2/3] ec: make use of added aligned buffers >> >> On Mon, 15 Sep 2014, Ma, Jianpeng wrote: >>> If we modify bufferlist::c_str() to bufferlist::c_str(bool align). >>> If (align) >>> Posix_memalign(data, CEPH_PAGE_SIZE, len) Else >>> Origin code. >> >> Alignment isn't really a bool, it's an int. c_str(int align=1) ? >> > I mean if we need a align memory after bufferlist::c_str. We can set the align = true; > Now bufferlist::c_str depend on the size when using rebuild if bufferlist have more prt. > > BTW, we also can change the rebuild() && rebuild(ptr). Merge two func into one rebuild(bool align). > By judge the parameter align to alloc align memory or not. > > Or am I missing something? I don't think there is a need for c_str(int align). We make every effort to allocate buffers that are properly aligned. If c_str() does not return an aligned buffer, the proper fix is to align the allocated buffer at the source, not to allocate a new aligned buffer and copy the content of the non aligned buffer into it. Do you see a reason why that would be a bad way to deal with alignment ? Cheers > > Jianpeng >> sage >> >>> >>> I think this is simple and correctly code. >>> >>> Jianpeng >>> Thanks! >>> >>>> -----Original Message----- >>>> From: ceph-devel-owner@xxxxxxxxxxxxxxx >>>> [mailto:ceph-devel-owner@xxxxxxxxxxxxxxx] On Behalf Of Loic Dachary >>>> Sent: Tuesday, September 16, 2014 1:20 AM >>>> To: Janne Grunau; ceph-devel@xxxxxxxxxxxxxxx >>>> Subject: Re: [PATCH 2/3] ec: make use of added aligned buffers >>>> >>>> Hi Janne, >>>> >>>> See below: >>>> >>>> On 15/09/2014 17:55, Janne Grunau wrote: >>>>> Requiring page aligned buffers and realigning the input if >>>>> necessary creates measurable oberhead. ceph_erasure_code_benchmark >>>>> is ~30% faster with this change for technique=reed_sol_van,k=2,m=1. >>>>> >>>>> Also prevents a misaligned buffer when >>>>> bufferlist::c_str(bufferlist) has to allocate a new buffer to >>>>> provide continuous one. See bug #9408 >>>>> >>>>> Signed-off-by: Janne Grunau <j@xxxxxxxxxx> >>>>> --- >>>>> src/erasure-code/ErasureCode.cc | 46 >>>>> +++++++++++++++++++++++++---------------- >>>>> src/erasure-code/ErasureCode.h | 3 ++- >>>>> 2 files changed, 30 insertions(+), 19 deletions(-) >>>>> >>>>> diff --git a/src/erasure-code/ErasureCode.cc >>>>> b/src/erasure-code/ErasureCode.cc index 5953f49..078f60b 100644 >>>>> --- a/src/erasure-code/ErasureCode.cc >>>>> +++ b/src/erasure-code/ErasureCode.cc >>>>> @@ -54,22 +54,38 @@ int >>>> ErasureCode::minimum_to_decode_with_cost(const >>>>> set<int> &want_to_read, } >>>>> >>>>> int ErasureCode::encode_prepare(const bufferlist &raw, >>>>> - bufferlist *prepared) const >>>>> + map<int, bufferlist> &encoded) >>>> const >>>>> { >>>>> unsigned int k = get_data_chunk_count(); >>>>> unsigned int m = get_chunk_count() - k; >>>>> unsigned blocksize = get_chunk_size(raw.length()); >>>>> - unsigned padded_length = blocksize * k; >>>>> - *prepared = raw; >>>>> - if (padded_length - raw.length() > 0) { >>>>> - bufferptr pad(padded_length - raw.length()); >>>>> - pad.zero(); >>>>> - prepared->push_back(pad); >>>>> + unsigned pad_len = blocksize * k - raw.length(); >>>>> + >>>>> + bufferlist prepared = raw; >>>>> + >>>>> + if (!prepared.is_aligned()) { >>>>> + prepared.rebuild_aligned(); >>>>> + } >>>>> + >>>>> + for (unsigned int i = 0; i < k - !!pad_len; i++) { >>>>> + int chunk_index = chunk_mapping.size() > 0 ? chunk_mapping[i] : i; >>>>> + bufferlist &chunk = encoded[chunk_index]; >>>>> + chunk.substr_of(prepared, i * blocksize, blocksize); } >>>> >>>> It is possible for more than one chunk to be padding. It's a border >>>> case but... for instance with alignment = 16, k=12 and in of length >>>> 1550 you end up with two padding chunks because the blocksize is 144. >>>> >>>>> + if (pad_len > 0) { >>>>> + int chunk_index = chunk_mapping.size() > 0 ? chunk_mapping[k >>>>> + - 1] : k - >>>> 1; >>>>> + bufferlist &chunk = encoded[chunk_index]; >>>>> + bufferptr padded(buffer::create_aligned(blocksize)); >>>>> + raw.copy((k - 1) * blocksize, blocksize - pad_len, padded.c_str()); >>>>> + padded.zero(blocksize - pad_len, pad_len); >>>>> + chunk.push_back(padded); >>>>> } >>>>> - unsigned coding_length = blocksize * m; >>>>> - bufferptr coding(buffer::create_page_aligned(coding_length)); >>>>> - prepared->push_back(coding); >>>>> - prepared->rebuild_page_aligned(); >>>>> + for (unsigned int i = k; i < k + m; i++) { >>>>> + int chunk_index = chunk_mapping.size() > 0 ? chunk_mapping[i] : i; >>>>> + bufferlist &chunk = encoded[chunk_index]; >>>>> + chunk.push_back(buffer::create_aligned(blocksize)); >>>>> + } >>>>> + >>>>> return 0; >>>>> } >>>>> >>>>> @@ -80,15 +96,9 @@ int ErasureCode::encode(const set<int> >>>> &want_to_encode, >>>>> unsigned int k = get_data_chunk_count(); >>>>> unsigned int m = get_chunk_count() - k; >>>>> bufferlist out; >>>>> - int err = encode_prepare(in, &out); >>>>> + int err = encode_prepare(in, *encoded); >>>>> if (err) >>>>> return err; >>>>> - unsigned blocksize = get_chunk_size(in.length()); >>>>> - for (unsigned int i = 0; i < k + m; i++) { >>>>> - int chunk_index = chunk_mapping.size() > 0 ? chunk_mapping[i] : i; >>>>> - bufferlist &chunk = (*encoded)[chunk_index]; >>>>> - chunk.substr_of(out, i * blocksize, blocksize); >>>>> - } >>>>> encode_chunks(want_to_encode, encoded); >>>>> for (unsigned int i = 0; i < k + m; i++) { >>>>> if (want_to_encode.count(i) == 0) diff --git >>>>> a/src/erasure-code/ErasureCode.h b/src/erasure-code/ErasureCode.h >>>>> index 7aaea95..62aa383 100644 >>>>> --- a/src/erasure-code/ErasureCode.h >>>>> +++ b/src/erasure-code/ErasureCode.h >>>>> @@ -46,7 +46,8 @@ namespace ceph { >>>>> const map<int, >> int> >>>> &available, >>>>> set<int> >> *minimum); >>>>> >>>>> - int encode_prepare(const bufferlist &raw, bufferlist *prepared) >> const; >>>>> + int encode_prepare(const bufferlist &raw, >>>>> + map<int, bufferlist> &encoded) const; >>>>> >>>>> virtual int encode(const set<int> &want_to_encode, >>>>> const bufferlist &in, >>>>> >>>> >>>> -- >>>> Lo?c Dachary, Artisan Logiciel Libre >>> >>> -- >>> To unsubscribe from this list: send the line "unsubscribe ceph-devel" >>> in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo >>> info at http://vger.kernel.org/majordomo-info.html >>> >>> > -- > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- Loïc Dachary, Artisan Logiciel Libre
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